You can buy these little aluminum trays with or without covers for pennies at places like Job Lot or Dollar Tree. The smallest sizes I've seen for about 12 cents a piece and the large ones for about 25 cents a piece. Or you can reuse them from places that offer salad bars.
My favorite method for storing and heating anything edible is glass, and that's what I use most of the time. But for things I want to put in long term freezer storage, this seems to be working fairly well. So far my chest freezer has turkey pot pie, vegetarian pot pie, and quiche stored in this way. I'll be moving on to fruit pies next but I wanted a few dinner options taken care of first.
The most space efficient way to seal it is to trace the top (widest) part of the pan on a piece of paper. Fold a sheet of aluminum foil in half and hold the paper against it while cutting out the circle. Place the foil sheets on the food portion first and then the circle of paper (which you can write the contents on). Pinch the lip of the tray around it and put the whole thing in a gallon sized bag to freeze and store. The bags can be reused over and over.