“…These studies have reported increased WTP associated with high-risk behavior (Buchbinder et al, 2004;Koblin et al, 1998;Meyers et al, 1994;Vlahov et al, 1994), younger age of initiation of injection , high perceived threat of HIV infection , lack of medical insurance (Koblin et al, 1998), having at least some college education (Buchbinder et al, 2004), and high knowledge about HIV and HIV vaccines (Koblin et al, 2000).…”