Kind of late replying to this subject, but here has been my experience FWIW...
We found someone who sold us 3 machines in various states of repair for $400. We scrounged parts from 2 to make 1 good one. Sold the remaining two for scrap after filling a box with some usable spare parts.
Loaded it up with about $60 from Sam's club at about .25 per can. 5 columns.
Vending them for 75 cents, could probably get a buck.
We have people who do nothing but pull up to buy soda. Kids will buy soda while parents are washing in the self-serves.
Never been vandalized (it's been almost a year now). Haven't made my $400 back yet on it, and it's probably costing me more in electricity than I care to know.
We did bolt the machine to concrete, the thing weighs a ton fully loaded, and they would have to rip the bottom of the machine out trying to steal it outright. All for maybe $40 worth of soda and change.
Plus we'll have a hi-res picture of them doing it, all the while the siren will be going off and the police on the way because it's alarmed as well.
Our soda machine isn't a moneymaker, it's a venus flytrap.