The dinner basics are probably cost effective: turkey, veggies, dressing, potatoes. Sweet potatoes - not sure what they cost right now. We were members of a CSA farm & have enough for Thanksgiving. Actually the dressing depends on what you do to it. I just put canned mushrooms in mine. I have other family that put a lot of extra such as oysters in it.
Pumpkin might be really high this year because of the drought. I went ahead and bought some canned last month - just in case. This year, apple pie will most likely be cheaper. Some items depend on whether you make them from scratch. I think of holiday dinners as the one time to get close to making things from scratch. I know that leader LOOSEINGIT / Cheryl gets her pumpkin from fresh pumpkin.
If you have freezer space, buying some items early might be more cost effective.
I make a green bean recipe that I use frozen whole green beans. The pricey part is it has balsamic vinegar. I had some family that didn't like the 1950's mushroom soup recipe. But all of them seem to like this: recipes.sparkpeople.com/recipe-detail.asp?
You can make your own dinner rolls a couple weeks in advance, then don't brown them to much before you freeze them and reheat.
It doesn't sound like you are planning on a lot of guests, but I usually count on guests for the dessert or perhaps salad.