Found out that you can buy custom items with NBT tags on them, from these shops no problem ( buying a sword with a custom name and enchantment). BUT if you say make a currency for players or better example trying to sell a shulker box full of a specific item in exchange for currency, the shop will allow any version of that item even if its not full of the specific item. "So if you wanted players to have to sell a diamond sword with the enchantment smite level 1 and get rewarded with 9 diamonds, a player could cheat and just sell the basic diamond sword and get 9 more diamonds and re-craft the swords!.

 Tested the new update and it seems to not function at all on my server (Only tried the creative shops). Tried using this on a regular world I had on my computer (just made to test the mod) and it crashes the whole game with a tick speed error. Tested to see if it is a mod that I have that is not pairing well by removing all of my mods except for the shops one and it is still not functional. I am unable to use the shops at all both the craftable shop and the creatvie shop.  Tested this on a brand new creative world.