In years past, if we've stayed at home, I've made a big turkey with oyster dressing (in the bird), mashed potatoes, gravy, and corn or green beans. If we stay at home, I'll make up a small veggie tray with dip, for munching on while we wait for the bird to finish roasting. I usually make a pumpkin pie (with fresh pumpkin), and either cupcakes or cookies for the kids.
The last two years, we've gone to my SIL's for Thanksgiving (since FIL was diagnosed with cancer). MIL made the turkey & dressing, and at least 2 pies, my two SIL's made most of the sides, and then I was asked to bring a veggie tray or an apple pie, and I usually made both. My other SIL brought some sort of dessert last year, and I think one person ate some.
I'm not sure what's going to happen this year though. It doesn't appear that my father in law is going to be with us much longer, maybe a month or so, if we're lucky (but stranger things have happened). But for right now, I'm going to plan on us being at home this Thanksgiving with me cooking.
If I end up cooking the whole dinner, I figure it cost us around $20 or so.