On many campuses one will find notices offering modest sums to undergraduates to participate in experiments. When the experimenter does not attract sufficiently many subjects to participate at the posted rate, does she raise it? Do undergraduates make counter offers? If not, why not?  An interesting contrast is medical research where there has arisen a class of human professional guinea pigs. They have a jobzine and the anthropologist Roberto Abadie has book on the subject. Prices paid to healthy subjects to participate in  trials vary and increase with the potential hazards. The jobzine I mention earlier provides ratings of various research organizations who carry out such studies. A number of questions come to mind immediately: how are prices determined, are subjects in a position to offer informed consent, should such contracts be forbidden and does relying on such subjects induce a selection bias?