Nacho bar?
Big bag of tortilla chips at costco, the big can of nacho cheese ( in a crock pot) and a big can of stagg chili (in a second crock pot) Put some thinned sour cream in a mayo squirter bottle. Bowl of diced tomatoies, bowl of lettuce.
Or a similar idea could be a baked potato bar. A 10 lb bag of baked potatoes can go a long way. I like to spray my washed potatoes with pam, wrap in foil, bake until done, then put them in a crock pot. (you can even cut them in hlaf before putting in).
I make my pigs n blankets from bridgeford bread dough, found in the frozen section usually near the frozen pie area. That would be much cheaper than using the canned biscuit dough.It's probably 3 bucks for the 3 loaf pack. A 3 pk of loaves, made up with hot dogs inside would certainly feed 20, but more likely double to triple that, depending on how much dough you use for each dog.
A big bowl of home made popcorn is inexpensive. I put alot of oil int he bottom of a pan, (double the depth of the kernels) then put it on almost high andf let it go. I dont even have to shake it. I know it's done when it starts really slowing down. Pour it in a bowl and season with salt and sugar only. (no butter). You can even mix a bit of cinnamon in the sugar if you want. Yummy stuff.