The i5-4690 is pretty close to the best you can get in that price range:
CPU: Intel Core i5-4690 3.5GHz Quad-Core Processor (€227.90 @ Caseking)
Total: €227.90
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-12-02 15:38 CET+0100