I'm looking for a new amp to play with a Squier Jazz. I got a Rumble 12 with the bass. Looking to upgrade to something a bit louder, probably 200-500 watts. Had GK recommended. I definitely want one used, to save cash. Trouble is I can't find a good site to buy from. Tried the classifieds here, but nothing for under $500 (max I can pay). Any good sites/links?