The ones I ordered already have their listings ended on eBay but with these links I'm sure you'll get the idea, be sure to contact the vendor regarding the specs before you actually place an order or risk errors.
Technically these will be the same ones you get from those pre-assembled kits, just picked out by the "pros" who know what works and what doesnt for a slight mark-up.
http://www.ebay.com/sch/sis.html?_kw...d=140635401011
http://www.ebay.com/sch/sis.html?_kw...d=320802087098