Do you have an AM3+ motherboard already? If not get "unpreferred"/
😉 After 11 years of AMD I finally built an Intel system and I'm kicking myself for waiting so long. iamlegend's suggestion of a Pentium G3258 is a good one. Low price, easy to overclock, low power usage even at 4.5 Ghz and better gaming performance overall than AMD FX-4300 or FX-6300. If you must go AMD, an FX-6300 is generally the "go to" budget processor of theirs. If you're in the US Newegg has an FX-4300 on sale for $84.99 right now (ends tonight).
http://www.newegg.com/Product/Product.aspx?Item=N82E16819113287