As Spamray has mentioned, the overarching rule on the forum is Caveat Emptor. The site "management" does not make any claims to guarantee the outcome of any group buy or sale conducted on the site.
We did, in recent years, take a couple steps to help buyers and attempt to make the process better. GB organizers are only permitted to run a limited number of buys at the same time, and newer members are not allowed to run GBs (some level of "trust" must be established first). Beyond that, it really is a matter of sending money to someone on the internet, and buyers must understand the risks involved with that.
All of the ideas outlined here seem to misinterpret the structure of geekhack. This is not a corporation or business, it is a forum run by volunteer enthusiasts in their free time. There is no legal involvement of any sort, and we don't have the resources to enter into agreements or partnerships with Paypal or any other corporations. There is no kickback from vendors or GB runners, or anything of that sort.