omg, well, I sympathise that all there money is used up elsewhere, but unless they are students, and their guests will be just so delighted to have a place to congregate full stop, then it's very tight. Especially as the chances are people would have brought a bottle anyway, so they have needlessly advertised how tight they are.
I am moving house soon so I know every cent is accounted for! but still, the difference between being generous and being eye-wateringly tight on this occasion is not worth it. So, they stump up for some some booze, but probably tuck away a few bottles aftwerwards! It's just not worth being so inhospitable.
Or you say to a few close friends, could you ever get me a bottle of diet coke/tonic on your way over!
But I'm Irish, there's no greater shame here than to be a mean host. My cousin was a mean host to my great aunt once and there are raised eyebrows years later!!
If you you can't afford booze, then invite them over for a coffee? or afternoon tea and do sandwiches and a shop bought cake! That's acceptable in my world, no idea if my world is the real world