If you care only about the price per pound, then you should buy from the store. Industrially raised turkeys and geese are kept for a very short time, just long enough to reach slaughter weight. They are intensively farmed in barns with thousands of birds, 24 hour light, high protein feed and little room to move.
If you care about providing high quality, wholesome food for you and your family, then you should raise them yourself. You cannot do it anywhere as cheaply; but that's not why any of raise our own meat birds. It's all about ensuring that the animals yo use for meat were treated humanely.
My geese sell for around $50 for Christmas. It is a fair price, as waterfowl only lay in winter. I have to keep them for up to 10 months and all the little costs do add up. I have never done turkeys, as goose is far superior food; but you can get them late in Summer for fattening prior to Thanksgiving. So I imagine it could possibly be less expensive than a goose.... but turkeys don't graze, while geese do, so that factors into the ammount of food they'll eat.