An Asus Eee Keyboard is useful as a desktop machine and you can install a C64 emulator on it. If you are buying this product, it's for the nostalgia factor (as I doubt they will be able to hit a commodity nettop/netbook price point).
An Asus Eee Keyboard has no Cherry switches, so, this is probably better built. And yes - nostalgia has something o do with buying this instead of the Asus or any other probably cheaper small PC.
So, how much would you pay for a computer unable to run Windows that can emulate a C64? Chances are, not much.
It wouldn't need to be much. Per one of my other posts in this thread [1] computers that can emulate a C64 (but lack a keyboard and other features of the original) have been sold in the past for around $20. I'm guessing the cost of the machine I am envisioning would be dominated by the cost of the Cherry keyswitches. I'd buy it for $100 and I bet they could make a nice profit margin selling it for even less than that.
You still need the space for one more computer (or one more keyboard), but I think it's a fair assessment. This one is more compelling to the space constrained who want to solve two problems (one almost nobody has - needing a C64) with only one computer.
And your solution is not constrained by the need to have a PC-like keyboard - it could be very faithful to the original C64. And I'd be delighted to buy one for US$ 100, as long as it was a C128D with an SD card for its hard drive.
My wife would kill me, of course, but there are things worth dying for.
I could give this to my son and he would still be able to browse the web, read his e-mail and do his class assignments. A c64 is a toy.