Not only is it welcomed and appreciated by the recipient, but buying it can be fun and rewarding as well. Make sure that the art can be exchanged. Ask before purchasing.
Many galleries offer a return for credit policy but make sure.
Spend a while thinking about the lifestyle of the person you are buying for. Finding something appropriate is critical. We all have many different interests, and with a little thought you will be able to find something surprising and unusual. These always make the best gifts. Allocate an appropriate budget.