Argh, see I'm kinda in this dilemma too.
I have the regular 3DS, but someone in my family has just bought a 3DS XL for ?104. After looking at it, I now really want one ;/
They said they will give me theirs, they literally only got it yesterday, and I could pay them the money, and they would get another.
So I thought, I'd sell my old iPhone 3GS for ?80, and just pay the ?30 extra. Or.. Sell the 3DS aswell, paying it all off, with a little left over. It's this, or sell the iPhone and keep the money, along with the original 3DS, meaning I basically walk away with ?80 extra.
I don't know what to do though, I really do want an XL!