There was a fairly lengthy thread on Pro Comp heads very recently, so I'd recommend doing a search for that thread. I tried to be analytical then, but now I'll just sum up my opinion by saying I would not run those heads on either of my small block ford's if Pro Comp payed me to use them.
About the best deal I've seen on aluminum heads is from www.tristatecylinderhead.com. They have Tri-Pro heads (Australian made I believe) for $800 a set complete.