The ReviewPost you see on
ViperAlley was customized to provide cross-linking between vendors and products; it is not something that is handled by ReviewPost out-of-the-box. (This is because the system isn't perfect and I never took the time to figure out how to take it beyond what I did for my site.)
ReviewPost also doesn't handle different forms of currency.
Both features would have to be modified to the actual product (maybe removing the average pricing altogether).