For that sort of money, you are not going to be able to get much in the way of a conventional mixer that is worth having. I would look at an 8-channel computer interface and a low-cost DAW such as Reaper and take it from there. In your price bracket, something like the PreSonus FireStudio Project is a reasonable entry-level interface unit with 8 microphone pre-amps and a FireWire interface. It comes with Studio One Artist software, but I think you will find Reaper is considerably better.
An interface such as this would allow you to capture 8 tracks of audio and mix using the computer. If you really don't need the equipment for live gigs at present, it does not seem worth spending a large part of the money on the mixing functions that can be done in the computer.