This may feel tacky to some but please save judgement. I think Costco is a great option for those with a very limited budget but a lot of people to feed. Their party platters like the sandwiches, shrimp cocktail, and meat and cheese are affordable. They feed up to 24 people per tray and cost around $40 each. They also have sheet cake thats $25 for 48 servings.
costcomenu.com/costco-party-platters-menu/
costcomenu.com/costco-wedding-cake/