Good luck finding a decent Intel CPU under $100. The I3 is okay, but surely won't be the best "gaming" option. Personally, I'd make the switch to AMD for a budget PC build. The FX 6300 (ive used before) is probably the BEST CPU for the money. Think about it, 6 cores for $100 with AMD or 4 cores for $200+ with Intel. AMD=Perfect for budget.
No, I'm not an AMD fanboy, ; ) I currently use an I5-4690k but have used the FX-6300 in the past.