Robert,
I was unable to attend the LV convention and missed the new and improved leather cleaning class. So I am not speaking from recent experience. However, I believe most will chime in that they charge much more than you suggest. I am charging more than that for normal fabric covered upholstery.
A standard sofa is approximately 6 – 7 feet long. at $12 per foot, that would be $84 for a sofa at most. I get $99 – $109 for normal fabrics.
With leather being more expensive, I believe the market will bear an even higher price. If the customer feels the furniture is worth more (and leather usually is), I expect they will be willing to pay more to have it cleaned well.
I’m betting you can easily charge $20 and up per linear foot for leather.
Mike