my band is using a ****ty crate amp for the mic, but you can barely hear it and it overdrives.

Im looking for an amp that i can use for the mic, or i might just buy a PA.

i dont have a price range, but up to 600 USD is good
600 will get you a cheap PA system for the whole band to use, if you buy enough mics later on.

Get a mixer and a pair of active speakers. That's enough for club gigging. I can't point to a specific brand, really, but I advise to save up a little more. Or get one speaker for rehearsals and get the second one later for gigs, once you have the money.
Quote by grifff
Do you plug your amp into the pa, or just the instrument into the pa?

It depends.

Microphones go into the PA.
Instruments get a microphone stuck in front of them.

Drums, vocals and acoustic guitars get mics. Electric guitars and basses are played through their amps, and each amp gets a mic.
It basically takes the sound of your amp and disperses it throughout the entire venue.