Great amp, crashed and burned after 30 hours... Buyer protection?

I agree with arctikdeth suggestions.  You must immediately call the seller and request a full refund and you should return the unit.   How did you pay for the unit?  Credit card charges allow to file a compliant and get your charges refunded.  I think PayPal has a similar claim process.  Based on the amplifier problems you described, I would return the amplifier to the seller, request a full refund and not agree to any repairs.  

I only use PayPal when I make a purchase.  Also check feedback on the seller. I have made many purchases on here and Ebay and never had a problem!

Thank you.... my buddy was screwed because the 30 hour point was after 63 days.... no recourse with anybody, seller said it worked for him and worked for my buddy, so tough luck.... repair shop told my buddy that the repair done on the amp previously was lucky that it even lasted that long... real hack job, counterfeit parts... I will definitely double check anything I buy, and do what you have all suggested... seller basically told my buddy to get lost... 

Two months is a long time to expect any kind of recoarse!

Yes, tough luck. He could try taking that person to the court, but the case would be hard to win, I guess. However, it appears that the seller didn't disclose the history of the unit, so there might be a chance.
But perhaps having the unit repaired would be a better course of action.
How do you recognize good people to deal with? Go with your intuition, slightest hesitation - don't buy, especially expensive things. Still, intuition will fail from time to time, there will be losses. So what? The important thing is not to lose too much.  When buying records off ebay I throw away probably one out of five, that's accceptable loss for me.