Yeah, that could seriously get into some pedo-ish issues.
Not that all older people are perverts, but it might make a young con-goer uneasy if a much older person were to "buy" them or whatever.
But if it was only eighteen and over, younger con goers might feel left out.
So I would say, if something like this was considered approproate, the age ranges would have to be relative and appropriate.
Like, fifteen & sixteen yearolds could only "buy" within their own age range, and eignteen and above could only "buy" within the age range.
That might make some people more comfortable, and not irritate overprotecrive parents. :?[/size]