To be honest, I don't see how this is "buying" trust though, you are just lending to users and if a member didn't really want to get scammed, then they will use a reliable escrow.
People on any other forums or any selling website has to build their reputation, otherwise who would trade with you or take you seriously if no one ever traded with you before? Everyone has to start somewhere.
For lending escrows are not needed,OP can choose right person to lend amount without getting anything as collateral as a beginner he don't have to complicate it too much.
This can be used as building reputation too because OP is not going to lose any amount by lending to the reputed members but when everything goes fine OP will get feedback which is trust.