I know you do not work that way at the moment but you wouldn't be holding the code hostage. You openly ask for donations right, and without these donations it would be difficult to do as much as you do for the zen cart right?

Well then, all I am saying is that you could say "if there are enough people out there that want a certain feature or add-on, then you will develop it for everyone" If all your users donated £1, the dev team would be able to commit alot more time to the programme.

It sounds like a fair deal and still by far the cheapest option for a cart solution. This is just my opinion of course.

Pete