This one’s fairly simple and straightforward. Buy a used vending machine on Craigslist and place this somewhere safe and obvious.
Price your products competitively and it will be used just for the convenience factor by guests.
The biggest threat to profitability is vandalism. Other than that, you’re guaranteed some relatively easy money.
Why pay someone else to vend and profit on your property when you can easily just do it yourself?
If your parents aren’t already doing it, you might as well see if you can personally invest in a machine and stock it yourself for personal profit.
If you have some vending experiences, share them in the comments section!