Curious about this as well.

I got the achievement just by not purchasing from the food vending machines. Spent money everywhere else without issue.

Yeah, not finished yet but the Devs confirmed me.

Anyway thanks Bob!

I didn't ever buy from the snack vending machine (waste my credits on that overpriced trash? As if) and didn't get it. I did use Mutamods like crazy, and the Heal-O-Dome healing early on, though. I did, however, check every single snack vending machine every time, and if it was broken I'd fix it, and that meticulosity only came in handy once, which was worth it.

I got it, never used the food machine obviously and even the heal o dome, I guess that's the problem.