I can see what Danny is saying here, if you go on other forums they are full of active group buys whereas it's only been recently with the 64mm tb, TDF exhaust and now with the RS Tuning remap that people have been receptive to using the forum to purchase things.
I've seen many posts where people float the idea of a group buy that gets lots of interest right up until crunch time and the deal falls flat because suddenly people have to cough up. Having said that I myself have sold quite a few bits through this forum but this is not the reason I am on it or came on it in the first place. For me it's first and foremost because I have a 200, the people that are on here, the subject area and the banter so I dont look at it solely as a business outlet.
As Litchy says it is beneficial for the traders and users to form good relationships to build awareness of products and it shouldn't always be about margins but there is a fine line.
A trader using any forum or business channel needs it to be viable to make a living just like everyone else, without that there would be no product development or progress at all which would be bad for us all.