A fruit salad can be made really inexpesive with a can of pineapple, two cut up apples, and grapes. See what fruit is on sale the week of the potluck.

Do you know how to make california rolls? They are pretty inexpensive to make. Most people like them.

How about making a fruit granata? Basically it is just pure fruit juice frozen and flaked with a fork when freezing. Could have some nice vanilla cookies to go with it. You could use an ice holder to put the granata in.

How about a vegetarian lasagna? Even something simple like sliced zucchini with tomato sauce and onions and seasonings would be a good idea. Cheap also.

A rice pilaf with diced up veggies.