I would do at least 75 people's worth (3/4 of 100) until you get a feel for the group appetite.
You need 2 18 to 20 quart electric roasters (about $40 each) to heat and transport the food. Each holds about 50 servings, and you would need 2 for this group.
For each meal, I would do:
bread, about 15 pounds, might be cornbread, biscuits, rolls, French, garlic, etc.
A heavy dessert, cobbler, dump cake, rice or bread pudding, done ahead.
A serious starch; rice, potato, pasta, hot or cold.
A serious bean; this could be baked beans, pintos, borrachos, refried, country beans with ham or meat, black beans; or a soup, or a cold bean salad such as Texas caviar or 3 bean salad; or red beans and rice with sausage and ham ends.
Something green, slaw, salad or vegetable. Broccoli is more popular that salad in this age group.
As for meat, you are looking at 20-40 pounds, depending on the dish. Your budget is $360 total. 20 pounds at $2 is affordable; 40 pounds of meat at $3 a pound is $120, so this meal would be a rare thing, when your skillful buying has built up a little surplus.
Best buys for meat; chicken leg quarters (standard package holds about 10 quarters, which would cover about 6 of your players), whole turkey (store brand, and see my "how to cook a frozen turkey" link for the easy way to do it. I pound whole makes 1 cup meat.) Pork shoulder, which can also be substituted for beef in many recipes. Locally, we get a product called "Ham ends and pieces" which is really good spiral ham odds and ends in a 3 pound package for $6- this is great for Scalloped potatoes or macaroni and ham.
Take a look at the basic budget entrees in big pots for help with ideas and amounts. Pastas you definitely want pasta casseroles.
Baked spaghetti, maybe with chicken
Red beans and rice
Ham and scalloped potatoes
Taco bar with beans and rice
Turkey or chicken tetrazzini
Baked potato bar with BBQ meat sauce; big potatoes
That should get you started. How long is football season, anyway?