I'm looking for a new amp (a combo), and I have no idea what to get. I want something that's powerful enough, probrably 100 watts, that's in the $500-700 range. I was looking at some Marshalls, but I really have no clue about amps. I play mostly Screamo and Post-Hardcore but I also play a lot of Indie. Does anyone have any suggestions?
I'm a person.
The B-52 AT-212 is a great amp for the money. Plenty of gain for your sceamo, and wonderful tone for the price. That's what I got with a similar price range.

For used, you can really go anyway you want. You could go for a Marshall DSL, or even a Peavey XXX... Try some out is what I suggest.
My Gear:
-Schecter C-1 Plus (Vintage Sunburst)
-B-52 AT-212 Tube Combo
-ZW-44 Zakk Wylde Overdrive
-Digitech RP350 Multi-Effects Pedal
-Hamer Slammer Strat Copy
^ Your saying that and you own an MG?

I'd take a Laney over any Marshall after the JCM800 any day.
i wouldn't go Vox if you only play heavier stuff, i'd try out the Marshall DSL and anything else you can find in your range.
The Gearz:

Schecter Omen 6
B-52 At-100 head + 4x12 cab
Yamaha EG303
Digitech Bad Monkey Overdrive