As far as I'm concerned, we already have most of stuff for sharing in the vault, new members can hardly find anything to post there for credits.
What The_Rock_Band said is perfectly reasonable - you SHOULD be able to see what you want to pay for as some kind of previews, this is common for any trading system. I've seen a lot of topic with collections whereas I'm looking for just a single track, but being unable to view the thread without a subscription is really frustrating - you'd bet your money/credit on a 50/50 that the track exist in that topic or not. This was also the reason I'm posting single track topic even if I already have a whole collection in one topic - that way guests can use the Search function to look up the track they are looking for. But then not everyone will be kind enough to do so.