I'm not sure, but was just talking about this with dh's mom today. ALL of our family lives 2 hours away and we hate always having to drive down there for holidays. Since we have the most room we have always taken on hosting thansgiving. BUT they love to cook so they bring most of the food and do the cooking.
We usually provide the turkey and will probably get it free from the grocery store. You know, spend x dollars, get a free turkey. We already spend the x dollars anyway.
I don't think we will have to spend much else - just provide some basics - maybe salad and rolls and drinks. Not planning to spend much but planning to eat well!
I get paper plates and all that from the dollar store. I probably don't even need to buy any this year, so many leftovers from years past. I'd be surprised if we spent $20 to feed 20 people. HAving a generous family, that loves to cook, helps a lot.