I don't know of any companies in the Midwest doing retinning; but do know two very good retinners located in New York: East Coast Tinning, and Atlantic Retinning. Another retinner, Rocky Mountain, located in Colorado, charges $5/in but computes by adding height to diameter. I'll let you do your own Google search for the links.
Prices at both of the eastern retinners are currently $4/in, with "inches" computed by multiplying height by diameter, so a 12 x 2 skillet would be $96. At Rocky Mountain, the same 12 x 2 skillet would cost $70.
Rocky Mountain charges $10/in for pots larger than 18in; remember though that an 18in pot the way they measure (diameter PLUS height) would be a very large pot.
All three companies have excellent reputations, and include dent removal and polishing as part of the price.
Shipping will be a major part of your cost. Unless you're working with a lot of pots or large sizes, you're probably best off using the Post Office's "If it fits, it ships" pricing.
BDL
Edited by boar_d_laze - 6/9/12 at 8:52am