There's now some competition for the tank market: EcoTech (which competes with Serlimar for waste disposal) has now gotten into the propane game with a company called, EcoGas. A number of things:
The location for tank exchange is way more convenient for people living in Noord - as opposed to schlepping all the way down to Arugas in the south by the airport, you can just go to Tanki Flip 109 (just south of the Super Do It - Shaba location) and exchange through the drive through - they even remove the tanks from your car! It was 24 AWG per 20 lb tank.
They also have an offer to convert properties to the large tanks (including installation) for free... just the 90 AWG deposit on the tank and then I'm sure there's a service contract involved for the regular filling. Details here:
https://www.facebook.com/EcoGasAruba/
It's nice to have some competition on the island!!