Depending on what you consider a "deal," and how far you're willing to travel for this, check through the catering menus of your favorite places.
Whenever I'm on the hunt for something similar, I just talk to someone at a restaurant that I like, and explain the situation with a general idea of what foods they make the I like, and would lend itself to reheating, or heating at home. Most restaurants would LOVE to work with you if they have someone knowledgeable about the operations, and not a worker bee that just thinks food for ten means ten sep entrees in ten styrofoam clamshells.
Grocery stores that can be trusted can excel at something like this. When Marianos had Todd's BBQ in them, I could always count on them for better than avg bbq feasts with sides and errthing. Mexican grocers like La Casa Del Pueblo and Jimenez have hooked me up with some REALLY good big meals for ten + with far less hassle than you'd think, and prices that made me question what some other places are smokin.
I'd also suggest Middle Eastern and Indian grocers that have prepared hot foods that you know are good. Off the beaten path, I know for a fact that I could hit Harlem Grocery down there near 100th and Harlem and ask for a bunch of falafel, stuffed falafels, greezy cheese stuffed "pies" and fresh from the oven, hot pita, lavash, fantastic hummus and baba g, all kinds of olives, hot pepper relish, labneh, then at home I could grill or bake some chicken parts, grill some steak parts and veggies, crisp the falafel and warm the pita in the oven, and have an absolutely STELLAR feast for dirt cheap. And I mean it would be FANTASTIC. You might have to call a few days ahead depending on how many falafel you'd want, but they usually have several dozen on hand early, especial on a Saturday. That's just an idea. One gentleman at the counter assured me if I called ahead of time, they'd be happy to work with me on hot foods, and special spicy sauces to go with them.
Pick a restaurant you like, and ask them. I usually go in with the mindset of, "I'm trying to pay you for your service. I am here, TRYING to pay you." I guarantee you that there will be restaurants chomping at the bit for your business. I also let them know that I understand some of the things that will make their lives easier - like if I'm planning on replating or serving the stuff in their foil pans? Just tell them - "listen - no need for it to be fancy, just slop it right in the pan, less work for you - it's all good. No napkins or silverware to worry about, just give me the food in pans, and I will come get it, and pay you money so you can make a profit. EASY PEASY."
On the cheap, Costco's a sneaky play, too. Before you brush me off, some of their food is more edible than I'd like to admit, it's just in HUGE portions, ie.
Shepherd's Pie, that Kirkland Pulled Pork in the refrig section is worth it for the ease to price ratio. A little pricier is that refrigerated "Sliced Roasted Sirloin" Plus, they've got rolls, desserts, and chips and mashed taters and shit in massive quantities.
Just ideas - tryna help.
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