Yep, I've also read about that. Atmega 32u4 are cheap, like 3-5 $, but the usb host shield costs like 30-40 $ which is unreal. I could get a whole arm soc with like 1 gb ram for that. Might as well get a Banana Pi, that way I could get bluetooth as well, if I need mobility(having the option of using both bluetooth and a cable is a fine thing since you don't always have the space or position to use cables). Another added benefit to using it will be the possibility for a web based api plus a web panel. Adding a small screen might be a fine idea as well.
But I guess I'd rather go cheap for now, so if someone finds cheap MAX3421 chips, please share.