Uh.
I don't get it.
If you sell a lot you are obviously making a profit. If you are making a profit you can compensate your mom for the charges.
Wait a second... judging by your profile, you are 20 years old. Why don't you use your own credit card? Why are you conforming to your mom's unreasonable demands. Does she even know how a credit card works?
There are so many things wrong with this post I don't know where to begin.
Man... just get your own credit card. I got my first one when I was 18. Change the CC account # on your eBay account, compensate your mom for the charges already present, and you're good to go. I don't see the big deal.
-Warik