It's a simple matter to connect a two channel amp to the preamp outs from the Integra. If you want to you could even connect another pair of front speakers to the new amp and leave the ones that are now conneted to the Integra. You can switch them off with the speaker on/off button when you want to play the new ones. The amp in the Integra will not be used when driving the new front amp with the pre-outs so it could still be used to drive other speakers.
As far as amps go, there should be plenty of good used amps for sale here within your budget. What did you have before?
As far as amps go, there should be plenty of good used amps for sale here within your budget. What did you have before?