Another American Girl Doll?

I have one American Girl Doll, which I bought from birthday money. I've been saving up for my AG Fund, and so far I have about enough money. But my dad told me a few months ago that my mom would get angry if I got another doll even if she was $20. That fact angers me because my friend has TWO dolls, and she didn't have to pay for ANYTHING! What should i do? My parents KNOW I want another doll, it's never mentioned, though. When I bring it up, my dad says, "Where is this going?" What should I do? I know I WON'T get a doll for my birthday OR Christmas.