It's a matter of space. In one of the larger shops 19xsomethingx8, you can have huge buy/sell walls, like my shop is starting to be, and like @usernameofdeath's shop already is. With a smaller shop, 15x12x6, there often isn't room for decor, and if you make the shop more pretty you lose space for signs, etc. However, the ugly, boxy shops will often repel visitors, even if your deals are the best in town. What you give up in order to maintain your profits is entirely up to you... for some, it's the decor... for others, it's not having buy signs in the shop... I would like to think that a shop, even a small one, can be both pretty and functional, and have several designs up in the market right now that are doing well, but it's never a sure thing.
there are different sized shops? I am just interested in a most cheap beginning but the market is crowded! I am veryt greedy when it comes for money! cuz i never have enough.
I used to make 20-40k (profit) a week from Station 14 since I didn't have that much money to buy things :/