I would suggest eBay. Some good masks pop up now and then. I would not however trust any sort of deal with Tyler H. at all. He's grown infamous for ripping people off and sending them nothing.
I haven't seen one I've been completely satisfied with yet.
The Rubber Gorilla one is nice but the proportions are a little off.
Tylers one is also nice but I've heard it's a little heavy for wear and the top of the head is a little off, although I did see pics of someone get excellent results by bondo-ing and reshaping the head.
The jaw line is all wrong on the Tyler one though....I've heard great things about the Rubber Gorrila one though. What ever you do, don't buy one directly from Electric Six.
I have the Rubber Gorilla one. Picked it up at a con over here in 2009. It is nice but it's a little stylized (you can tell it's made by rubber gorilla they have there own distinctive style). Also it's quite big. Excellent for display though.
I have Tyler's original mold and have produced a couple nice pieces from it. I made mine thicker for display purposes, but it can be poured thinner using a softer resin for wearing.