Do you plan on replacing your stock speakers as well or are you leaving them as is?
Even the weakest of decent amps on the market today will probably pop those factory cardboard speakers.
The Pioneer GM-4000F is a nice amp for the money, a little inefficient though at 35RMSx4@4 and 40RMSx4@2, but then again 4 speakers at 35RMS each is pretty darned loud.
If you're looking for even less expensive check eaby for a soundstream amp, which aren't really all that bad, or you could look for a lightening audio amp. Those are cheap and have Rockford Fosgate circuitry in them..... hrm, I see three typos in here alread, guess I'll stop now.