if you need free why not go with a free vpn service or even a paid one. since its shared anyways.
but on the topic that price seems just right on. i doubt you find anything cheaper. at least i havent seen any then again im not in the market for shared proxyies..
the real reason is what you using them for, that may help alot, cause some proxy are great for this and piss poor for that, and some are great at that and piss poor at this, you understand...
but thats smart not to every jump in to something head first not really knowing , and when i buy private proxies (i know you looking for shared) i always try to get a test one, if i cant ill just buy one (single) to test and see if it works for what i want before i purchase a lot. cause even private proxies wont work for what you want sometime, imagine shared.