What I'm hearing is similar to the publishing business. A gallery may reasonably charge a "hanging fee" of twenty bucks or so. Everything after that they are supposed to make from commissions -- 40 to 60% there. Although there are some extremely prestigious galleries that might up that hanging fee to a hundred bucks, something in the thousand-dollar range is a clear sign you are dealing with a vanity gallery. (Like publishing...there is a growing number of publishers that ask a reading fee now, but it is nickel-and-dime stuff. A reading fee in the hundreds of dollars means their income doesn't come from selling books, it comes from selling an imaginary service to YOU.)