The new Mac Mini starts at $700+ and still requires a separate monitor, keyboard, mouse, speakers etc. Certainly not meant to be portable, so if you're a developer and want a laptop (as many developers do) your next choice is a MacBook which is well over $1k.

You can buy some shitty Windows laptop to make Android apps on for $400. Will it be a good experience? Absolutely not; but at least you can get it done.