Actually, Horizon CHOOSES not to compete with Tower. I've met the owner of Horizon in person while i was in the hobby business, and I asked him about that.
He said it was because they didn't want to step on the toes of their biggest customers, the hobby shops.
I got my XXXNT AD2 for $290. check horizon's price on it. my LHS has the XXXS Graphite for about $40 cheaper than Horizon does. GP has Tower, and they make a BUTTLOAD of money...think about it. they sell their products for about the same price as most hobby shops do, but OBVIOUSLY, since they ARE a distributor, they could very very easily sell it for well under a hobby shop's cost.
thanks to both of them for NOT putting our LHS's out of business when they easily could, we'd all suffer if hobby shops died out in favor of online commerce.
If you don't allow yourself to make mistakes, you'll never allow yourself to succeed