cheaper and best don't go together my friend. you'll have to pick either a cheap one or the best one. but if you're buying your first DSLR, I'd suggest d3100, d5000, or d5100, maybe even d90 if you prefer Nikon. On the Canon side any of  T3, T1i, T2i, or T3i would do fine. If you ask me which one would I choose if I had to. I'd say d5100 for Nikon, and T2i in case of Canon.
Buying used locally can save money.