LOL! A customer and I were discussing that same thing this morning!
I barbecue quite a bit and use maybe, what, twenty gallons per year? A typical commercial walkbehind cutting eight hours per day five day per week for 42 weeks will use 1680 gallons. Propane companies know this (I do). Trust me here, I helped build the program. They are quite happy to supply either a bulk dispenser or a cylinder rack along with the cylinders.
If you guys want to play with my program feel free to visit here. You can put-in your own numbers:
Clean Fuel LPG Propane Conversions, Eco-friendly
Have fun with it!!
By the way, you kinda get ripped-off with the cylinder exchange. You pay a premium for a new 20# cylinder and then when you exchange you could get a 1965 refurb. That and they short you 1/3 gallon each visit. You wind up paying about $4.00 per gallon. Convenience has a price...