@dhechler – if you already discounted the price based on the fact that you already had the code written, then give it to them now! You should tell them that the price was reduced so much because you already had most of it written. That way you can give it to them right away.
@ChristopherBurton – if the client ever found at that another client has the exact same module already and you charged them full price for it, they will not be happy. It isn’t devaluing the product at all, as you’ve already (theoretically) charged somebody full price for it. Anything you charge beyond that is bonus! I’m not saying give it to them for free, it’s still your product to sell, but selling it for full price seems unethical (and dangerous).