Refill my Sodastream with Dry Ice- 60L How to Refill for $2.75 (ish)

Dried ice IS Co2 gas and here's how I refill my SodaStream 60L canister at home in 10 minutes. I've been re-filling from 14oz to 18oz (weight) without issues. Takes about 60-90 minutes until it's fully compressed after filling/closing the bottle.

I go to Ralphs, a big CA grocery store chain, and they have a big dry ice chest in the meat dept. The "Penguin" brand by AirGas is "food grade". I ask for 1 lb. It comes in 5lb blocks, and they have to break it up for me. I'll take whatever they can give me close to a pound in weight, and then adjust after I hammer it up. No need for a scale if they are weighing it for you, though I do have a scale now.
I don't know how much "evaporates" over 20 minutes, but I go straight home and start the process.
The price varies, from $2.50 to $4.50 in 2021. I'm wondering if Covid 19 vaccine storage issues and natural disasters affect the production and distribution, and ultimately the price.

Replace the O-ring every 3-4 refills. They get brittle and flat. Home Depot, Danco brand #96730, 10 pack, $2.50 #13 size, 7/8"od-x11/16"id x 3/32nd. I've stopped putting silicone on the threads or the O ring. Saliva might be just as good.
Empty bottle with valve: 24.5oz without valve 19.3. add 15-16 oz of dry ice- total weight after fill- 35-36oz
Using the Sodastream Diet Cola flavor mix for instance, takes about 18ml to taste good (imho) and costs 25 cents per serving. Using the Narvon brand diet cola, takes 45ml, and is not as good. Tastes like diet root beer is mixed into it. I bought in the 5 gallon restaurant size, it equals 12 cents per serving. I like the Sodastream soda flavors. But at $6. per bottle, you can buy a can of original soda at Costco for the same price. If you buy the Sodastream refill gas, it's more expensive than the actual can of soda. So, the only way to make this whole concept cost less, but taste like the brands you enjoy, is to refill with dry ice.