All my amps have been bought second (or third/fourth etc) hand and I've not had any issues. You might be unlucky and get a problem, but that's part and parcel of buying used gear. As for amps, save up. 200 will not get you anywhere near to a good valve amp. If you can make do with what you've got just now, keep playing it and buy something worthwhile. Don't just splash 200 on something that you'll be wanting to upgrade in 12months time. Second hand Marshall's are likely your best bet, DSL50 and JCM900 SL-X's are great amps. Stay away from the JCM900 Dual Reverbs though, not as good. The TSL's are pretty horrible also. They've just brought out a 6505 combo, might be something to consider