How can I get around the whole Can't use Amazon gift card to buy other gift cards thing?

I've been saving up for a laptop, and I've got $50 in Amazon gift cards now. I haven't uploaded them yet. However, I found out that I will save a LOT of money by buying the laptop I want on Bestbuy. I know $50 isn't a lot but it was supposed to go towards the laptop, and it's going to take me a while if I have to start from the beginning. So what can I do? How can I get a best buy gift card instead?