You should have exactly three: one for the kitchen, one for the man cave and one for the pool.
As for margarita machines, I'll second the Margaritaville one.
I have a kitchen fridge, a beer fridge in the garage, a wine fridge in the kitchen and a (hole for a) beer fridge in the game room. Another fridge outside would raise my carbon footprint to just above of China's.
Looked at the Margaritaville machine in BBB tonight, but not sure it's what I want. Essentially, I'm looking for a bar-style (spinning) machine, with a tap on the front so that I can set it and forget it. They all seem to be too large for my needs (and way too expensive).