While it's possible you might get scammed, you might not. Just a matter of how much is $50 to you, if it's just a drop in the bucket, why not?
I once bought a site off of flippa for $1200. The guy made that in less than 2 months on adsense, and his organic se traffic was rising daily so i figured it was worth the risk. I ended up making 40-45 a day for 5 months before that google images update killed it dead. If i would of came in here asking, i would of got the same above replies, i'm sure. No risk, no reward, but only risk what you can afford to lose.