How to go about a Request?

My goal is to be the possessor of a graphics tablet. Probably a Wacom Bamboo Fun tablet. I’ve been wanting one for a while and want to try my hand at digital art. I want to ask my parents for one. My mother has faith in my traditional art, as do my friends. My parents are already paying for my $565 summer camp fee, and we recently had a vacation to Disney World. The tablet ranges from $60 – $90. Would it be selfish of me to ask for one? Or should I wait until after camp to ask? I would pay for it myself if I was of the age where I could get a job.