Unfortunately these things happen when you trade on forums, but then you can still get ripped off on Ebay, or even buying from other websites. I ordered some non bike stuff online, only for the company to go bust and not post my stuff. Yes it is a risk, and you do lose out, but with the majority of transactions you come out on top.
I have purchased a few items from the members here, and for a lot less than I would of paid elsewhere. I've dealt with very helpful people who are willing to post overseas for a little extra cash.
I have yet to be ripped off, I have been drastically over charged on postage, but have not had anything lost or my money taken by a scammer.
There are risks, but they are low, perhaps for sale ads could be limited to those members with a post count above a certain amount, or those that have posted their bikes. (I do appreciate the irony of this, as I have a low post count, have not yet posted pics of my bike and have bits for sale, but if the rules changed I would happily delete my advert)
If you post a list of the bits you need I'll have a loo through my boxes, if I have anything you need it is yours for free, and I suspect others may do the same.