I have one for sale!!! It is new in the box and it came with 2 extra rechargeable batteries. It is the 1:6 size. The battery will last about 2 hours each but in 4by it doesn't last as long. They are so fun but I ended up with 4 of them(don't ask) and I sold 2 already, I have one more. Wal-Mart carries them but they are on FOREVER backorder. It's $120 with the 3 rechargeable batteries, I think Wal-Mart lists it for $119 with one rechargeable battery. Of course there would be shipping charges but I don't even know if anyone is interested in it, yet. I also have the DVD that came with it. It is educational and kinda cool. I just looked at they're website(funrise.com) and the batteries are $14.99 a piece if you buy them.
I also got with it a rock terrain that you can put together in your house and roll over it. It's fun for a while but you gotta get outside with it!! When I looked at the website I didn't see the terrain for sale.
Anyway I thought I would post this here and see if actual enthusiasts were interested since it is sold out at the stores and maybe you have been trying to find one.