The price for a towerbimini.com unit is a deterrent for me as well. I'll probably end up getting one, though. I like the look, and the only other option I've found is this:
http://www.bigairwaketowers.com/bimini/bigairbimini/, which IMO looks just as nice as the tower bimini, but doesn't look like it would fold up well at all, which is a must for me since I have to fold down the tower to store it in my garage.