The problem with the Micro nowadays is that it's very very hard to find one at any kind of reasonable price. I suspect it never sold that much, so the supply of units in good condition is very low, and hence stupid prices on eBay.

I've bought myself a modded original Gameboy Advance with a modern backlit IPS screen and it's a marvel, absolutely love this thing. Spent a small fortune re-buying all my childhood games for it just so I can play them again. And yes, the form factor is nearly perfect.