That sounds very reasonable.I did not read all the posts so try a gas and welding place in your area, I use Wesco and 20lbs is 15. on exchange for food grade bottle...FWIW
https://www.earlbeck.com/
Around here for 20# I pay around $30 for either a fill at 3 places, or just swap for a food/beverage grade cylinder at Praxair here. Haven't found a better price yet, I had called around...
Some quotes were almost double that.