Thinking about the numbers.. the average McDonald's kitchen, at a midsize store when I worked there many moons ago, all by itself, had between 2 and 6 people in it. At full staff, there were two assembly lines with two people each, one guy on the grill, and one guy starting orders by preparing the buns (the initiator). At low times, one guy on the line, one guy on the grill.

Assuming a reasonably busy location where there is no such thing as a "slow time" (airport, central metro area, etc), that means you have to pay six people around $8 an hour for 8 hours. Works out to $384/day on kitchen labor, give or take.

$2688/week, $139,776/yr. (And that's before taxes, local wage variances and so on - this is a very rough, very conservative estimate)

There's no way this thing will cost less than $150k - a shake/ice cream machine costs aroud 50-75k for a much, much more simple set of parts (liquid pumps, an auger, and a compressor). And that's before you get into maintenance costs and the cost of having a single point of failure.

Example: One of your kitchen guys gets sick, you can usually call in a replacement, shift someone from elsewhere in the store, or just run one person down and deal with it. The Burgermaker 9000, on the other hand, say the tomato slicer breaks? You're down. Completely and totally.

Combine that with the insane time to break even and see even a penny of ROI.. it ain't happening. Not anytime soon.