Refilling with an adapter hose and valves rig is quite easy. You must purchase the adapter and a 20lb CO2 tank, +/-$125 all-in, but after that, my cost to refill is just over $1 each based on a $22/20# CO2 tank refill cost in my market. It takes about 10 minutes to fill a canister, start to finish, and is far easier than any dry ice method of refill. Just make sure your existing blue cylinders haven’t expired (date stamp on bottom). If they have, send them in via the traditional refill method and get new tanks w a future expiration date. Then go back to self-refill.

Example Adapter link. $37: CGA320 G1/2 CO2 Cylinder Refill... https://www.amazon.com/dp/B08H5G92ZR?ref=ppx_pop_mob_ap_share