Some players have had trouble in finding Seeds and other Items at the Weekly Bazaar. My own Grand Bazaar Walkthrough/General Guide lists the items that have appeared in my own files in various Seasons, before and after expansions, but there are players who have not found all these items on offer in their games.
Essentially, the principles by which new items in all Harvest Moon and Rune Factory games usually are one of the following:
1. The total of Items one has shipped. For example, some actions that unlocked new options in other games included: 100 of each of 4 types of Spring Crops, 100 Cheese created in a Maker and so on
2. The total one has spent at a specific shop. For example, in Sunshine Islands, new pets were unlocked by the total one spent at the Animal Supplies Shop.
3. The purchase of a specific item. For example, in HM DS/Cute DS, one had to buy the Round Table from the Shopping Channel in order to unlock the ability to expand the Farmhouse.
4. The appearance of new Characters. For example, in Sunshine Islands, it was the appearance of a specific number of members of the Ranch Team that would unlock Sheep.
5. A specific percentage of 'completion' in one or more aspects of the game. Bazaar expansions in Grand Bazaar depend upon this.
6. A specific Friendship/Affection Level with another Character in the game.
In other words, if specific items fail to appear at your Weekly Bazaar, it is possible that specific purchases on your part may unlock the items you need. In all my files, the Brush appeared at Felix's Stall the week after I purchased my first Livestock animal. Once I purchased the Brush, the Bell appeared. When I purchased the Bell, the Stethoscope appeared. When I purchased the Stethoscope, the Cat Bell and Dog Bone appeared. It was at the end of the first Summer, I believe that the Cat Bell and Dog Bone first appeared.
My Character always purchases all possible upgrades as quickly as possible. She therefore had purchased all three Cookware Utensils, had upgraded her Storage and purchased 2 Chickens and 2 Cows before the end of the first Summer. She had purchased all items sold by Raul and all Seeds and other items sold by Chen and Sherry. She had ordered a Storage upgrade from Gannon. She had steadily increased Friendship Levels with all Characters in Zephyr Village. She had purchased Cooked Dishes from Joan and added a fair number of Recipes to her Cookbook. She had used all three Windmills. Whether or not any of these purchases or actions affected the appearance of any new items at any Stall, I do not know.
Other players have not found the Cat Bell or Dog Bone at Felix's Stall even after purchasing all Ranch Tools including the Stethoscope. My first instinct was to ask whether or not they had achieved the first Bazaar expansion. It is possible that you will not be able to purchase these items until the Bazaar has been expanded once. If, however, any Player has not expanded the Bazaar, but has been able to purchase Cat Bell or Dog Bone, I will know that this is not the requirement... I will be interested to hear from players about this.
The point I have been trying to make here is that you usually can unlock all new options without knowing precisely how you are doing it simply by diligent action in all areas of life.
In fact, unlocking Cats and Dogs at Enrique's Amazing Animals Stall is based on the number of Chickens or Livestock you have purchased previously. If you purchase four Chickens, you will unlock Cats. If you purchase four Livestock Animals, he will begin to sell Dogs.
If, however, you are unable to unlock any item that you want or need as quickly as you would wish, the Multiplayer option offers a method of obtaining those items.
Crop Seeds and Tree Seeds that have not appeared in your own game can be purchased at a Neighbourhood Bazaar at another Player's Stall in Multiplayer Mode. The Cat Bell actually can be sold there as well. Cooked Dishes that are purchased in Multiplayer Mode are sold WITH their Recipes. This is a way to add more Recipes to your Cookbook. Fish and Insects can be sold at Neighbourhood Bazaars but when you purchase them, they will not be added to your own collection list. You actually have to catch them yourself in order to add them to the Lists in your Farm Assets Menu.
Most Fish that are purchased at another Player's Stall in Multiplayer Mode can be used as ingredients in Recipes. There are Fish that cannot be used in the Kitchen, even when your Character caught them in your own village. Among these are the Ayumodoki, the Bluegill and the Moray Eel.
Many different Fish can be used to create such Dishes as Fish Stew, Fish Paste and Grilled Fish. Although the Recipe will specify a particular variety, you can use others successfully by trial and error.
For example, the Recipe for Sashimi specifies Tuna but Sculpin can be used as well.
Similarly, although the Recipe for Fish Stew specifies Silver Goby, Dark Sleeper, Gin-Buna and Mackerel all can be used to create the Dish. If you need a specific type of Fish to create a Dish but the Fish cannot be caught in the current season, you either can visit another village in that Season or buy the Fish from another player.
There is an aspect of Cooking that has confused players which is that of 'Cooking with Recipe'. Recipes in Grand Bazaar are item-specific. In other words, if you use a Silver Goby to create Fish Stew, and the game records that as the Recipe, only Silver Goby will be recognised as the ingredient to make Fish Stew when you use the option to 'Cook with Recipe'. In other words, if you KNOW that your Mackerel can be used to make Fish Stew, but Silver Goby is given as the Ingredient in the Recipe, the game will tell you that you do not have the necessary ingredients to make Fish Stew. To use different ingredients, you have to 'Cook Without Recipe'. (The actual wording of the prompt may be different. I am writing from memory at the moment.) In other words, to use a different Fish such as a Mackerel, choose the option to 'Cook without Recipe', then place the Fish manually in the Ingredient Slot.
After the Dish is made, the game will ask if you wish to change the Recipe. If you do so, it will give Mackerel now as the Ingredient instead of Silver Coby.
In other Harvest Moon games, Fish usually are distinguished only by size. Recipes require Medium Fish for the most part, irrespective of variety. Grand Bazaar distinguishes Fish by species rather than size.
In terms of Multiplayer sessions, there are a few tips that can be very useful. Visits to another Player's village should be made on a day when all of his/her Crops are ripe. In such a case, EVERY player, including the Host will be able to harvest every Crop in the field.
If it is Friday in your game and you need to rid yourself of items, a Multiplayer game is a good way to achieve this without loss of profit as you can sell items at another player's Stall. Remember not to buy all the items on display, however, until you have completed your own sales. Once the Stall is 'sold out', no more transactions can occur. If, therefore, you intend to fish and/or dive for items, it is best to leave one item on another player's Stall until you have completed all your own activities so that you can sell excess items before the Multiplayer game comes to an end.
Incidentally, another Tip where Fishing is concerned is to do as much as possible when the weather is nastiest. Fishing in a Hurricane or Snowstorm can bring great rewards, even with a Short Fishing Rod. The Hotel Screen appears to be best for most ocean Fish. Evidently, the storm affects the tides and brings them into the river during the worst storms.