Trying to convince my parents to let me subscribe.

Here's the thing. I'm a fifteen year old who's been using this site for a year. I've watched pretty much all the videos, and listened to all the bombcasts. So, obviously I want to support the guys who have provided me so much entertainment. Trying to convey this to my parents is tough. I'm not trying to mooch off them, I'd literally pay them back immediately, but I have to use their credit card. They still are using the logical approach and seeing they I'm not exactly getting value for my money. I think the value I've got is all the stuff from the past they have provided and I really want to listen to the bombcasts on time, but they don't get paying for a website since the only other websites that charge are all porn. So, is anyone else having trouble convincing their parents? Any tips?