The Shop never has everything all at once, just the normal stock and whatever is added for currently ongoing events.
Here is a link to the
collectible tier list thread as well as a link directly to
the Google spreadsheet which shows the prices things have tended to sell for, with images attached.
-Mars- has also made a
thread dedicated to displaying them in color coordinated order. Here is a link to
the color coordinated Google spreadsheet itself.
With those two combined, you can get a general sense of what all of the tradable collectibles are that you can acquire, what they're called and how much you might expect to pay others to acquire them (unless they return to the Shop as part of an event).
-Apples- also made a thread a while back called
List of all Collectibles by Set which, aside from those, also shows some of the collectibles that were or are only released as event or contest prizes.
Some of those need to be updated to include the new collectibles from the Sakura Week and April Fool's event, like the White, Blue, and Purple Sakuras and the Strawberry Soft Serve, but they'll get to it when they have time.