I want to say they're the Professional Products throttle bodies that are rebadged as Summit's own brand. If that's the case, and the pic on Summit's site looks like it is, I have absolutely no problem with my 70mm PP TB. I think it has a nice feature where it gives you some adjustability of the TPS. I don't think I paid that much for my PP one, but Summit has the best customer service out of any vendor I've dealt with, so I'd never hesitate to order it from them instead of saving $5-10.
I bought my Summit Racing 75mm TB for just $160 and it's a very well made piece. The adjustable TPS feature really is nice but mine didn't need adjustment at all (the TPS voltage was 0.963v right out of the box). The only small fly in the ointment was having to drill out the bolt holes to 10mm diameter 'cause they were only 8mm and too small for the mounting bolts to pass through.