On another forum to which I belong, when a reputable, senior member conducts a trade with a new or unestablished member, it is expected that the unestablished member ships the merchandise or makes a payment prior to the senior member fulfilling his/her portion of the transaction. Like this forum now has, there is a feedback system in place whereby you can track the number of positive/negative transactions all members have, and you can read comments posted by the members who've traded with that member before. This seems to consistently work. In the rare case that an unestablished member is unwilling to send first, the two parties have agreed to ship the items to a neutral third party, usually a moderator, who completes the transaction by shipping the items to their appropriate destinations (without receiving monetary compensation). This is a lot to ask of a moderator, but thankfully it is rarely requested. I'd say that about 40-50 transactions for gold and silver bullion are completed daily on the other forum I'm referring to. Just some thoughts . . .
EDIT: I like the new rules put in place, and I very much support the feedback tracking system. Thank you Snowball.