If I remember right, MFGquote had some kind of feedback thing, though, from what I could tell, it was basically useless.
I'll agree with Matt, unless its a fairly small company, the buyers don't have a heck of a lot to do with it after the POs are cut. What happens when idiot QC guy rejects your parts because they can't read a blue print or fails it for "shinyness" even though it calls out a 250 finish. Or the idiots that send you prints that are flat out wrong and won't mate with another part that you had no print for. Or probably the biggest problem, you quote 60 days and when you don't deliver in 3 days your on their sh**list? I assume the supplier has feedback control over the buyer. Categories of
1) promptness of issueing a formal PO
2) Do they supply good prints, I can give you a pretty good quote on a crappy print, but if you want the part right, I better be able to tell if thats a 2.030, 2.050 or 2.080 +-.001. Also specs called out in the drawing.
3) If the buyer is supplying material or castings, are they getting them to you in a timely fashion, or are they sitting on it until past the due date, and are they supplying the correct amount, I love quoting a quantity of 50 and then the material shows up and there is only enough for 30, and then they say, well, we only need 25. Guess what, that costs you more.
4) Is QC retarded and rejecting your parts for stupid reasons?
5) do they pay????
I would say being a middle man could be very difficult. A simple one time feedback like E-bay probably wouldn't be sufficient. Something that could be filled out as the transaction progresses, up until and even after the check has been issued, like when they come back after 2 years and decide you didn't make the part like they wanted even though it was to print and passed QC.
An absolute idiot buyer could really screw a small shop. Possibly side by side feedback on the same page. Buyer complains that the job was not shipped on time, other side of the page, supplier could post that the buyer did not supply castings until 3 days after the due date. Buyer: supplier scrapped 15 of 30 castings. Supplier: 25 of the 30 castings were out of spec and I bent 10 of them into shape, get a QC department.