Strange, Full member used to cost that much. Sorry for the misleading info, I guess you should search around for more recent account sellers. (Haven't been able to find any recently)
lol, I also tried to search onthis forum and found that the full member accounts are easily available at 0.02 BTC to 0.03 BTC, and pot Full member accounts are available at less than 0.015. you can see on the reference links below
reference 1
reference 2
while at one place on auction I saw that a legendary account sold at 0.42 BTC, and on another posts a person is selling his hero account at 0.35 BTC