I would say to sell the ones that might fetch more money by themselves, like other people have mentioned. But since you said you don't want to do that, I can only tell you that I would probably not buy a "grab bag" of g3's unless they were really cheap- like a dollar for 5 of them or something. I already have most of them and am looking for specific ones. If I saw your lot on ebay (or here) I would be more likely to go for it, because I could get the ones that I still need and then sell the ones that I don't. That's the fastest way to deal with them, and the best way for them to become Someone Else's Problem. An adorable and colorful problem, of course!
You could also just post your picture again in the "for sale" section and see who offers you money for which ones. The ones that are left could be put up for sale in a big lump, if there are any left. (If it were me, I would probably start with offering choice for $5, then when that peters out, lower the price to $2, then fifty cents.)
I love pictures of huge groups of ponies, by the way. They make me smile every time.