Re: A good metal/rock amp (need recommendations)
Well, I'm generally not a fan of solid state amps, but if you want 30 watts or under and lots of gain and distortion that's probably your best bet for under $500.
Check out the Roland CubeX 30 or a Vox Valvertonix. There is also Line 6 Spider. Most guys who are serious about good tone hate the Line 6, but I guess the amp does have some usable presets if you want Metal sounds.
Anyway, check out the 3 of those, but again, for your budget you are going to either get a low end tube amp or a higher end solid state. Another option is to get a used tube amp, but generally the lowest wattage you'll get on those is 50 and 50 tube watts is LOUD!