What is an excellent affordable combo/head for punk music?

What kind of sound does it have, is it growly, punchy, does it cut through?

Growly, puncy, and cuts through are some of the most often used adjectives to describe those GK RB amps. I'd still try and find one of the newer 700RB-iis if it were me, as you can find them just at $300 if you look/negotiate a bit - but if you can find a good deal on an older GK RB head more power to you.