Maybe you got screwed. How could you know?
Let me speak from one of the worst experiences of my young life:
I registered CamRoulette.com the exact same night I heard about ChatRoulette, which was sometime last December. I had originally planned to make a clone site, but got very busy with my marketing. The domain sat, nothing came of it.
One day I was offered $700 for the domain. I was stunned and surprised and immediately agreed, just like you. The next morning, I was offered $1200. I don't know what made me think it was right, but I instead agreed to that deal and then immediately pushed the domain and made the transaction. I then told the original buyer that also I said he can have the domain in an email, I found a better offer that next morning.
One month later, the
domain resold for $151,000.
Very shortly after,
I was hit with a $150,300 lawsuit. (This is extra detail not exactly relevant to your situation, but that just goes to show how serious things get, I suppose.)
I would never, ever agree to sell a domain in the same 3-day span that I get an offer like that. Give it some time to marinate. There's a reason he offered so much, probably.
