I've always wondered.
This year I got a chance to compare, since we had the opportunity to eat a pasture-raised turkey on Thanksgving Day followed by our own turkey dinner on Friday. The free-range turkey was delivered fresh and cost over $4 per pound. I think I paid about $1.29 per pound for our frozen Butterball. So this allows us to compare fresh with frozen, as well.
My family said they couldn't detect a significant difference in taste between the two birds. Both were roasted in bags and were incredibly delicious and moist.
So, for over three times the price, the value (in our opinions) would only be in the pleasure or satisfaction you may receive from knowing your turkey's provenance. If how your turkey as treated when it was alive is important to you, or you're worried about what it may have been fed or injected with, then you may feel that a pasture-raised, organic turkey is worth the price differential. However,if taste and budget are your criteria, I say go with the Butterball and use the extra money buy the rest of dinner plus dessert and drinks!
But if it is important to you to eat locally and you have a strong environmental concerns, by all means follow your conscience. After all, money isn't everything!