Free: Contests & Raffles.
7 mpg. That's all I can think about.
Any junkyard or trans shop should be able to set you up, those C6 truck converters must be a dime a dozen. If you really want new, I'd order it from Summit or Jegs. I'd think a torque converter with 114K on it wouldn't need replaced though? They're one of the more durable items.