I've worked on a few hospital run trials. The stipend for a subject was usually $50 a visit. Some trials involved us trying to make them motion sick, others involved a ride in a hyperbaric chamber. In all cases they were participating in a double blind drug trial of some sort.
In order for a hospital to run a human trial, the researchers have to hold to an incredible level of perfect. Internal Review Boards are merciless, and the amount of paperwork could drive one mad. It's hell for the researchers, great for the subjects. In order to even touch you, we needed to first give you a free physical, blood workup, cardiac testing (tilt table, sonograph), pregnancy test, and on and on and on. And you got a stipend for that day of tests.
I wouldn't hesitate to take part in any sort of research being done in a hospital. The free screenings are worth the trouble alone. The stipends aren't always huge, but 50 bucks for 3 20 minute spins on a tilt chair is pretty damned good pay for a college student. No matter what, you know that it is the absolute safest work that could possibly be done. There is always a slim risk associated with a new drug trial, but it's less hazardous then driving to work. Plus, sometimes it really is valuable data your contributing.
I'd be a little more apprehensive about going right through a drug company or lab. In theory, they have to deal with the same regulations that a hospital does, but I doubt thats the case in reality. If they aren't seeking FDA approval actively, and word the release correctly, they can give you just about anything they want. I just wouldn't feel comfortable doing that even if the stipends are much larger.
-Local