I have trading stands at CF during week or so, also I am byuing and selling through stands pretty often.
And i found misses and ways for improvement.
1. Multiply containers for 1 trading slot. Really, look at Bubbey`s stands.

He buying only 1 type of item. And uses long row of stalls. Yes, they looks cool, but not handy for him. Also if half of cupboards filled, i need to check 20-30 buttons to find one empty.
It would be nice to see status «full» or «not working» at least (slightly red tint for the slot) and variable for api (so CF report will show this status).
Easiest way is multiply red and green hands. Not only like now (many slots to one container) but like one slot with many containers.
To prevent mess with hands:
a) dropped on the ground just disappear, like flour.
b) stand`s slot have second interface with «kill all hands» buttons: all reds or greens for 1 slot, all reds for whole stand, all greens for whole stand, all for this stand. Last three should have confirmation dialog.
2. Quantity fields for selling items.
It is pain in the butt to split coins or opium. Split, split and split…
Also i can`t ask price 0.08 kg of opium. Only 1 unit (it can be from 0.01 to 0.5 kg).
It would be great to toss 100 coins in the container, write 3 coins for 0.03 opium and enjoy.
Present system limits ability to sold 3 apples for 2 oranges for example.
This system exist already, when stand grabs some coins from stack in my pocket. So please expand it!
Bying some tea from bucket or even barrel will be coolest even just for fun: take a mug, buy honeybun and some tea, sit and relax!
3. I want to buy that what i have not at all!
For example, i am pretty new, but i got 139 gold coins and can`t pay 140 in a few weeks.
And i want to buy troll belt. A haven`t any. How should i choose it for buying slot?
System should be reworked to interface with fast-search through all items.
4. Seller`s note to slot (optional).
Ability to put parchment into slot. It may be like «Achtung! This curio cause quicksilver poisoning, one point each» or teaching parchment for this item i.e.
5. My trading stand is mainly for new players. But I can`t change the price to dead rabbit, for example. Thee same with few things.
I can`t set certain sort of cheese, there is only «cheese» as type. BTW Selecting type or certain item like berries/fruits/food/lingonberry is good thing! Very handy! May be it can work to shortlist search, like that: i want to buy troll`s hide, clicking «choose» on raw rabbit hide and i have list of all raw hides possible.
So this part needs more polishing.
I can test barter stands more. Ask me if you need it and intend to work with.
Anyway, it will not kill private trading in bulk, cuz we have wheelbarrows and private agreements for supply.
And sometimes it is easier to sell glass key for storage to sell few CBS of goods at once. I like the idea of glass key so much BTW!
1 and 2 together will lead for huge simple personal storages. I can put copper coins into 1 cupboard and fill my storage. Connect all and have ability for fast grabbing some food for dinner, without running among cupboards and remembering where i tossed another 300 mushrooms.