Yes, usually a minimum of $50 over my regular stretch charge for that size.
By the way, gallery wraps are a good way to distinguish yourself from the competition, especially the big box competition. Not only will most big box competitors not do gallery wraps, some won't even stretch a canvas for a customer unless they are also selling a frame with it. Hey, I know we all want to sell the frames, too, but I can bring in up to $300 (depending on size) for the job, plus I've got the customer. So suck it up, folks -- we can't afford to turn away customers with cash in their paws.