What you get in the grocery store is a factory raised Broad Breasted turkey. It, like the CX Chicken, was designed to grow very fast and large. They are typically processed at about 10-14 weeks. You can find BBs at local farms that have been grass raised and they're usually processed at 14 weeks. What most of us raise and what the OP is talking about are Heritage Breed turkeys. These are turkeys that have not been developed like the BBs and represent many of the original gene pools. They are much better at foraging and grow much slower and often smaller. A heritage bird is usually processed at about 24 weeks. They have to be cooked much lower temp and slower to be tender. I cook mine in a covered roaster with stock in the bottom.I'm very curious about this. We never have an option; we just get what's available at the grocery store. So I'm enjoying reading this discussion.
Organic is a good start. But from there I know nothing about turkeys, aside from the wild ones that roam or woods, and that other wild one from my younger years.