I did 3 of these, never again. Between the money values changing and shipping everything out, I lost a lot of money on the last one. I'd rather save up a list and pay the shipping myself.
Also, consider that you pay for your parts and your portion of the shipping, then you have to pay for shipping to you from whoever ran the group buy. You don't end up saving hardly any money at all, especially if you ordered a larger part or 2. The whole thing will take a couple months at best.
The funny thing about "no feelers" in Group buys is that they almost all start as feelers haha.