gift etiquette

Sometimes in the course of fieldwork someone else does a big favor for you - whether it's a local resident who returns an expensive gizmo that you left behind, or a guy at the facility you're working at who spends his lunch hour wielding a forklift to help you load all your supplies.

When I was working in big field programs run by my (male) coworkers, the default was to buy the favor-giver a case of beer in appreciation.

When I was running my own field programs later on, it felt... weird to buy a random guy beer. Also, I'm fundamentally a rule-follower and buying booze in the course of an environmental investigation set off internal alarms.

I settled on a compromise - buy them lunch! But it was still sort of awkward, especially if I was working in an area where nobody had ever seen a woman in steel-toe boots. I wanted to thank them, not imply anything else.

Have any of my field-type readers run into this? Do you buy beer (or other things) to return favors, or is this a cultural oddity specific to my area?