Am I wrong for asking for it back?

I gave my mom 50$ for a really nice camera.

I gave her a payment, to show I was serious about getting it.

I ended up getting my uncle's camera so I wanted my money back. Logical response right? Money I worked for, (babysat and whatnot) We are not the richest people, and my dad is out of work. He is going back next week. So if she needed the money for bills, I wish she would have told me. I would let her have it.

Am I wrong for asking for my money back?

She said she used it on my Christmas gifts, in which she used all my relatives money to buy it, so why did you need mine?

This is not the first time it has occurred. She took my brothers 40 from my aunt this Christmas. Also, I spent about a year collecting change and I got 100 from it, but she took all of it. My dados a terribly stingy man when it comes to money. I just don't know how to feel towards the situation.