I don't think there are discounts just for this forum or for them being a sponsored vendor however I know HHP offers perodic sales/discounts on their own.
HHP installed the cam and tuned my srt. Josh, Bruce, and Don are great and easy to work with. When I was setting up the work to be done I ended up calling them because I had some questions. The quote I ended up with was better then the price that was listed on their webpage.