It too bad Apple hasn't realised that an user might have several computers and limited deskspace. It would be very handy if one could use one kbd with many devices at the same time.
I have a Logitech K380 wireless kbd (10€ from flea market) which can pair with 3 devices and you can "hotswap" it between the devices by choosing them from the yellow F-keys. Works fine. One thing that is better than Apple Magic Kbd is that it buffers typing better, so I can type my password while the computer is still waking up. With Apples kbd I need to wait for the pw-field to go active before it accepts input. Seems like there is no buffer at all but direct input only. The battery life is also much better on Logitech.
Keyboard feel is quite close to Apples, little less resistance when button is pressed but I think its ok. Neither is a high end kbd in any way. And IMHO Magic is overpriced to what it is. I still think the Extended KBD I & II were the best of Apple kbds this far.
There is also a full size K580 (~60€). And I've heard that the Logitech MX-series is quite nice, but more expensive. They have even mechanical Mac-versions @150€ for a MX Mechanical Mac Mini.
Ps. I too have several Magic keyboards for my desktop macs. 3 of them work, one has sticky enter-key (fixable?) and one has a dead radio.