This guy may be pretty good, not sure what all your requirements are on space and bandwidth though: http://forums.digitalpoint.com/showthread.php?t=371392
i wouldn't even bother with proxies on a shared server, It will obviously be oversold or the resources will be worn down from other proxy owners like you looking for shared hosting. You need a VPS to avoid these pitfalls. PM if we can work with you. Regards!