Penguin dry ice (food safe) can be found in 4500 supermarket locations in the US. At $1.50 a pound it takes $3 to fill a 130L SodaStream carbonator bottle. Once the cap is screwed back on the solid CO2 will undergo sublimation until the pressure rises to a high enough level whereby all the CO2 then liquefies. My guess is that everyone on this board owns a SodaStream and hates the high refill prices. Google Penguin dry ice for their store locator to find a supermarket in your area code. Also check out the YouTube video for one method on refilling. I have 3 130 liter bottles and the nearest Staples is 15 miles away. Staples wanted over $100 with tax to exchange all 3. Instead I bought 6.5 pounds of dry ice from my local (half mile) Publix for $10 and now I've got 3 full bottles. I put the block of dry ice in a pillow case and hammered it into a powder. With a funnel I shoveled 2 pounds into each bottle. Took 20 minutes. Works perfect.
I seen this video on Youtube. It got me thinking of doing this myself but after unscrewing the cap multiple timea it will eventually weaken. If there is an oring involved you will likely destroy that in time.Its not a big deal to replace but the whole purpose of swapping these tanks is safety. I imagine the tanks are tested for leaks. If your co2 bottle has been tampered with and it blows up in your face, Sodastream will not be liable. Thats why these bottles have dates and bar codes. To track them. Not trying to rain on your parade but play this game at your own risk.
The Heisenberg of soda. :) I'm gonna go ahead and keep paying my $15 every couple of months, but glad to hear you've discovered this. I'll safely stay Long with the assumption that 99.999% of the population will also just use the exchange program and not choose to pound dry ice in their pillowcases or have any sublimation going on in their households. :) Good luck!