How many lessons are too much/ too expensive?

Okay so currently, I have a brother who takes piano lessons which cost $120 a month but that's basically all my parents steadily pay for him. I take percussion lessons which are $160 a month. I also recently got a guitar which cost $100 but that was my christmas/birthday present. Still, that's expensive and it just happened. Now I really want to take art lessons. Really badly. They are about $17.50 per lesson ($250 for 14 weeks) but I really want them. Is that too much expense on me? I know there is no harm in asking, but I don't want to be a really expensive spoiled kid, y'know? As for how rich/poor our family is, we're just a bit over average. Thanks for your advice!