Unfortunately thats not a viable option - The trader rating system is an excellent tool, intended for precisely that purpose so we are all hoping Prank is able to get it working again shortly.
There have been plenty of traders with good ratings who have turned around and jipped someone at one point or another so as a buyer, moderators recommend using a degree of caution and exercising basic common sense when dealing with someone online. Satisfy yourself that the seller is legitimate, and make sure you know enough about them to put your mind at ease before handing over any money. As a rule of thumb, if you are skeptical, don't proceed. If you ask a seller for some of their particulars or contact information and they are reluctant to provide the info you request, abort on the purchase.
Moderators on this forum take a proactive role in keeping the classifieds area as safe as possible and there are a massive number of bad traders that have been caught out and banned as a result of the tireless efforts of the SAU mod team so while this work continues day in day out, we again ask every member to be careful and when it doubt, purchase elsewhere.