Yea they said them main things to watch out for were the materials for the diaphragm and the casting they used. Here is the one i was looking at:
Out of all of them it looks to be the best constructed for the price.

60MM EXTERNAL MANIFOLD WASTEGATE+TURBO BOOST CONTROLLER : eBay Motors (item 140336122654 end time Mar-24-10 15:46:52 PDT)