I hate plastic cutlery, so I've bought odd lots of old silverplate knives
and forks at sales and "junque" shops. When we've had a big group--say 50
people--I just use them plus my regular silver. Generally, people don't need
spoons at buffets.

I have to admit that I have enough nice china dinner plates for about 70
people. (I come from a family of china fanatics. )I just put out a few
patterns and let them pick.

I used to have an annual party for about 50. I rented some round tables and
chairs and cloths to cover them, and set them up here and there around the
first floor to augment the drop leaf tables I already have. I always use my
own linen or cotton napkins because I really dislike those polyester ones
you can rent. (I also have a lot of napkins...) I also rented glasses,
because I really do not like to use plastic ones and that is one thing I do
not have enough of.

It can actually be surprisingly cheap to rent some of that stuff, especially
glasses, and especially if you pick it up yourself and avoid the delivery
fee. And you don't have to wash them!