Seems reasonable to me. Am i the only one wondering why if it is simply a cae of seeing a psychiatrist and "getting a script" the guy wouldn't just do it himself and save the $500? If he is paying someone else good money to be the guy going into the docs office, then chances are there is a VERY good reason he's getting another party to do it for him. In this case seems clear that the reason would be that there is potential cirminal risk involved with the person essentially obtaining meds for fraudulent purposes. As to your thoughts on suspicion, well if he can convince the doc that he needs the script then why owuld he arouse any suspicion for returning and needing more of the meds his ailment requires him to take.
Sounds like a stupid idea if you ask me.
Have fun getting tangled up in drug trafficking though. Sounds to me like you've already got your mind set and despite peoples comments will try and justify it somehow regardless. If he's paying you $500, then that means the script/meds you are supplyinh him will be worth mroe than $500, once you're down that road you might as well just skip being the middle man and make all that money yourself