If all you need is a lower, and it's a standard run-of-the-mill lower - you'll probably come out even if you just go to a shop and buy one.
Because with the transfer fee - you probably won't be saving much, if any, anyway. Unless, of course, the shop is selling a $45 lower for $80+...which does happen.
Call around a few shops and ask if they have any lowers in stock and the prices. You may be surprised.