I don't mind the link, but in addition to what's already in the store options, there should be an option similar to what osCommerce has. Just "Powered by Ubercart".

I wouldn't want my store to say it's powered by "free software". It may make the store look cheap (to the customer, that is)

You have a point that you "work hard" and "spend a lot of time", but don't forget all the community's contributions and support that it provides.