"i've set a goal to carry work by artists that customers can't find anywhere else, and i want the store to carry work that is avant-garde and unexpected. however, one of my buyers has been purchasing the ugliest vases in the world and other things our customers are highly unlikely to buy. he says he really wants to put the store on the map, and that's what i want too, but he's taking too great a risk. what should i do? "

You should Set an example of being very honest with artists and with customers, giving both accurate information and fair prices.
In artistic industy, reputation is much more valuable than any form of profit because the products which exchanged in this industry are extremely subjective to value. If your goodname gone due to a mere profit, both artist and customers will unlikely interested in hearing your opinion in the future.