The glass Pyrex ("snapware") is awesome. Costco has great sale prices on them, every few months. IIRC it was like $24 (for a 16 ? piece set - 8 dishes + 8 lids. Something like that.)
I usually freeze in a ziploc bag (soups, sauces, and individual things that won't stick together like pancakes), sometimes with the food wrapped in saran wrap and/or foil first. The bags get rinsed out and reused.
For casseroles and other foods that I will be heating in the oven, I line the dish I will use to bake it with saran wrap. Put in the food, and freeze it.in the dish. After it's frozen, I take it out of the dish and wrap it with the saran wrap. It comes out of the dish like a brick but holds its shape. So, the food is ready to be baked in the casserole dish -- but my dish isn't tied up in the freezer.