Those XTD clutches go for really cheap, but why would they cost 1/2 of what most major brands sell for?

I personaly would get a company thats been around for decades and built up a good reputation.

Call up Clutch City. Like i told you, hes a great japanese (probably korean) guy, local custom shops buy clutches from him. He charges $115 for the Exedy oem replacements, which is about $10 more if you buy from Ebay. I personally would support someone locally, and you can see it before you buy it.
http://www.clutchcityonline.com/
Clutch installation usually run between $200-300