What denomination of currency are you talking about for your budget? To be honest, when it comes to price vs. performance, Intel has a very hard time matching AMD for anything less than $250 for both the CPU and MB combined.
There are folks on this board who will advise you that anything less than a i5 2500K is not worth it, but you will spend $200 on a i5 2500K alone. For that price, you can get a Phenom II 955 and an AM3 mainboard, while you would still have to spend about $100 more on the i5 to buy a mainboard. Granted, you get about 35-40% improved performance, but you pay for it.