Reading the guy's history, the dude obviously does not come from the best upbringing. It's hard for me not to feel for the guy. I had some pretty rough years myself, age 19 to 25 or so were a nightmare for me. Part of my problems were my own fault, some of them were not. Going to college and having no financial support from my family was very hard and depressing, which lead me to making some pretty dumb decisions. I won't go into details, but I will say I highly doubt the OP started this thread with the intent to rip anyone off.
When I was 19, an internet friend of mine lent me $100 for a bus ticket to Dallas to play Team Fortress Classic in a tournament. I did not ask for it, but he insisted because my team needed me for the tournament, he was the leader, and a good guy. I thanked and promised him I would pay him back. It's been over 10 years and I still haven't paid him back. I still feel bad about it, for a long time that $100 I owed stuck in the back of my mind. I always wanted to pay the guy back, but there was a stretch of time where $100 was a lot of money for me. I'd definitely feel the loss of that $100, I would've definitely had to make some sacrifices to pay that $100, even if that sacrifice was something petty like a video game or beer. When you don't have shit and are barely making ends meet, that video game or beer/weed might be the only thing in your life that doesn't suck or make you depressed. I rationalized not paying the money knowing the guy who gave it to me was well off financially. That $100 for him would just make the number in his bank account go higher, while the $100 for me represented tangible things I would need/want in the near future. If I ever run into him again, I will gladly pay him back, and thank him for not badgering me or being a dick about it, as it just would've been another thing in my life to bring me down. Dorimukyasuto probably avoids you because he knows he fucked up and it just makes him feel like shit whenever he thinks about it. At least that is how I felt about the $100 I owed.
Not too sure what my point is, but, Dorimukyasuto is probably a decent dude deep down, just having some issues finding his way through life (and probably lacking some key guidance). I hope he did not start the thread or accept your money with the intent of ripping someone off for drugs.
Knowing what I know, and what I've been through life, I'd just let it go. Years from now, you may get your money back from him, with some added interest, but don't expect anything.