The scammers was pretty smart, but how can you be making such a mistake, why dont you suggest an Escrow yourself than letting them do the job of getting the Escrow Service? And by the way, there are lots of trusted sites for buying coupons online and they all have good reputation. I dont know why most of you would prefer going through some random guys you find in forums.
By the way, its quite easy to find out this guy was a scammers cause first the link he sent you wasnt from him and you didnt even bother to verify whether it is him or not. Next he offered to give 20% off the main price, that should have ringed a bell in your head that it is SCAM!. Just a random guy saying he would give you 20% off the main price. Well, thats his luck.