FIRST: you need to frame your art so that the frame compliments the work and helps show it off. Expensive framing may actually defeat the purpose of selling your art and may even detract from your work. Many people may want to choose their own frame. I don't think it quite works out well - unless you are doing your own framing, matting, etc. People aren't usually buying the frame - unless it is an "old master" or something and it's the original frame that back then they made or some reputable frame maker made for them. Even when I was doing shows - I was selling my art - not the frame and charged ONLY what I paid for the framing. IF you are selling them yourself - you might make a couple more bucks out of your time and effort.
if it's limited it should be higher. but then again if no one knows who you are it may not make a difference. people are buying the art, not the frame, but a good frame attracts better. if you watch pawn stars, the first thing they do is chuck the frame and get a really good one.