Depends on your budget. Are you building a new comp or upgrading an old one? If upgrading, you need to get a cpu based off the socket your mobo supports, so check into that. For botting cheaply i would go with an amd 8 core, can be had for 150 i believe. Your going to need an am3 socket mobo though. Also, 8 gogs of ram should decf be enough for 8-10 bots, but if you want you could go 12. I wouldnt waste money on more than that, you wont use it.