Not to say the Subway prices are reasonable, but when you think about the cost of pop in the park. Doubling a standard price is not out of the ordinary. I can usually get a 2 liter for less than 2 dollars or a 20 ounce for a little more than a buck. A 20 ounce at the park is $3. The subway by me is I think $3.60 for a 6" Ham, $3.80 for a Turkey. The $5 footlongs are for a limited time only. It's possible some stores could continue it on their own.
All that being said, I have no intentions of paying $7 for a 6" sub. But, I also never had any intentions of buying a $3 soda.