Just a thought/suggestion, why not have different levels of badges? I.e. Bronze supporter - $15, silver supporter - $30, gold supporter - $60, or something to that effect.
That way you guys can potentially gain more revenue and also the members that do contribute extra are recognised, by all, via the different badges. I for one know that I would like to contribute more than $15.
I know that R182 above has just gone and purchased a quantity of 2 but the only people that will ever know that are the moderators and himself.
Anyway, just a thought. Hopefully don't cop heat for it.