I hate to say it, but it sounds like you have cheap and/or inconsiderate friends. I know times are tough right now but...
If the invitation doesn't clearly spell out my responsibilities, I email or call and ask what I can bring to help out.
Upon my first invitation aboard the boat of a new friend, I always present the skipper with a bottle of port or rum.
S/V Old Shoes
1973 Pearson 30 #255