DonkeyOatey posted a reasonable combo.
If you wanted stronger, I would suggest a i5-4690K and a Z97 based motherboard.
A conservative overclock gets you to 4.0, even with the stock cooler.
If you live near a microcenter, they will sell you a i5-4690K for $200
A Z97 based motherboard should be around $100; most any will do.