www.goodtoknow.co.uk/recipes/pictures/31381/50-quick-and-easy-canapes

If I were planning this party, I would do it in 2 parts; an appetizer/starter table with a punch and/or cocktail/sangria, then the dinner table.

An appetizer arrangement is important, even with a simple meal and here is why:

A self-catered buffet is a real challenge to the organizers, and things don't always come together as smoothly as hoped. By planning and setting up an appetizer area or "nibble table" which is ready when the guests begin to arrive, the cooks and servers have time to complete the arrangement of the dinner buffet. This is especially critical if there are children among the guests, or there is a wait before dinner, as at a wedding reception.

This does not have to be complicated. Three items, plus a punch and/or cocktail/sangria. Typically, includes a fruit tray, a cheese tray and an attractive dip or spread, but you would want to modify with your dinner plan; or you can go with a dinner theme such as TexMex with chips, salsas, Texas caviar and guacamole; Italian with bruschetta or antipasto; maybe shrimps or other cold seafood, if budget permits.

One appetizer service area is needed for each 100 guests.

As far as the sandwich fillings/meats, per 100, for a full sandwich:

22 pounds ready to serve meats
10 pounds cheeses
9 pounds roasted red peppers
6 pounds grilled onions, if used
17 pounds loaf bread
OR about 150 rolls

For the sake of the budget, you might do for 100 with the Italian meats and 100 with deli sliced turkey and ham, and do mixed platters. Some meat could be good salami, less costly than the others.

Here is an option for going beef-
www.beeffoodservice.com/recipe.aspx?id=4157

Tuscan style cannellini salad- per 10-12

32 ounces Cannellini beans (drained and rinsed if canned)(about 4 cups)
8 ounces julienned Sun Ripened Dried Tomatoes
1/2 tsp. Crushed Garlic
1/3 c. Extra Virgin Olive oil
1/2 tsp. salt
1/2 tsp. pepper
1/4c. chopped flat leaf parsley
1/3 c. basil chiffonade
1/2 c. Sliced Roasted Red Bell Peppers
1/2 tsp. red pepper flakes
1/2 c. shaved parmesan

Place the beans in a large mixing bowl. Add the olive oil, sundried tomatoes and garlic. Chop the parsley. To chiffonade the basil, stack the leaves on top of one another and roll up like a cigar. Slice into thin strips. Add the basil, parsley, red pepper, black pepper and salt. Mix thoroughly. Sprinkle the parmesan on top before serving.

This is a nice flavored butter:

1 stick unsalted butter, softened
2 Tbsp. Sun Dried Tomatoes finely chopped & drained
1/2 tsp. anchovy paste
1/4 tsp. fresh orange zest, finely grated
1/4 tsp. fresh rosemary, finely chopped
1/8 tsp. salt
1/8 tsp. black pepper

Pulse together all ingredients in a food processor until tomato is finely chopped and butter is pale pink.

Transfer to a sheet of wax or parchment paper and roll into a log about 1-1/2 inches thick.

Twist ends of paper to enclose butter and chill until firm, about 30 minutes

The potato salad, you want about 35 pounds potatoes per 100

The antipasto tray on this site would give helpful guidance about amounts.

You might consider adding a dessert buffet full of dainty Italian bites and coffee to give a sense of great abundance to your party. People love desserts.