What I made:

Lasagne
[Note: Instructions are for my mom's version, without forgetting mozzarella;
Ingredients:
Approximately 12 lasagna noodles (a twelve-ounce box of pasta is more than enough for one pan of lasagne; two pounds made enough for three pans with a little left over)
1 pound each ground beef and Italian sausage, crumbled, cooked, and drained
enough of your favorite pasta sauce to just moisten the meat -- don't use too much (I make my mom's sauce from scratch, and I'd say I use around a few cups for one pan of lasagne. Mom's sauce ALWAYS has parmesan added at the end, so you might want to do that)
1 to 1.5 pounds mozzarella, shredded
1 to 1.5 pounds ricotta
1 egg
salt/pepper
1/2 to 1 cup parmesan cheese, grated or shredded
Get all set up:
1) Cook lasagna noodles until they're almost done (I'd estimate 6 or 8 minutes); drain and set aside in a bowl of cool water
2) Mix together meats and sauce
3) Mix ricotta with the egg, some salt, and plenty of pepper
Preheat the oven to 350F. In a 9x13 or so pan, layer the lasagna in this order (when I say "sauce", I mean the meat/sauce mixture). Steps 11-13 are not a typo: mom says it's necessary to do them that way in order to keep the mozzarella from drying out.
1) Enough sauce to cover the bottom of the pan
2) Lasagne noodles, lengthwise in one layer
3) 1/2 of the ricotta
4) 1/3 of the remaining sauce
5) 1/3 of the mozzarella
6) Noodles, sidewise in one layer
7) remaining ricotta
8) The second 1/3 of the sauce
9) The second 1/3 of the mozzarella
10) Noodles, lengthwise in one layer
11) Remaining mozzarella
12) Remaining sauce
13) All the parmesan
Bake at 350F for 60-90 minutes, uncovered. [To make ahead, wrap well and refrigerate up to 2 days or freeze up to 6 months. To reheat from frozen, either thaw overnight or add around one hour to cooking time. Today, I did a slow reheat, since we were off doing laundry before dinner. 2.5 hours at 275F and the last 30 minutes at 350F was perfect, but I found the noodles a little mushy.]

How we liked it:
Cost per serving:
Ten large servings (or eight HUGE ones, huger than any sane person could eat).
Total: $1.56 per serving (or $1.95 per HUGE serving)
Noodles: $1
ground beef: $2
sausage: $1.50
sauce: $2.50 (including the parmesan)
mozzarella: $3.50
ricotta: $3
egg: 10 cents
salt/pepper: negligible
parmesan: $2