Good question. I have not seen one. Along with price is access - often one can't get the RV anywhere near the propane dispenser.
We don't use that much propane, so don't worry so much over price. Fill when needed and we are somewhere with access.
Vince and Susan
2011 Tiffin Phaeton 40QTH (Cummins ISC/Freightliner)
Flat towing a modified 2005 Jeep (Rubicon Wrangler)
Previously a 2002 Fleetwood Pace Arrow 37A and a 1995 Safari Trek 2830.