Yes, but it still adds up to more in the end. The cheapest within driving distance I've found [1] is half the cost to refill the sodamistic 60L bottle from what sodamistic charges, and almost half the cost of refilling the 5LB tank, but the 5LB tank holds 5x more CO2, so after 2-3 refills you're already losing money compared to a DIY solution when accounting for cost of the whole setup.

[1] https://www.sodamistic.com/CO2.html

Also higher pressures are better obviously. Another tip is to use cold water because that apparently absorbs CO2 better.

You can also carbonate wine. My girlfriend was very excited to be able to buy cheaper white and rose wines and just carbonate them instead of buying more expensive bottles of sparkling wine.

Once you start kegging your homebrew, you'll wonder why you didn't do it sooner.

After primary fermentation, I siphon from my carboy into a 5 gal corny keg, then I hook it up to my CO2. Turn the pressure up to maybe 20-30 PSI (strictly for carbonating; turn it down for serving) for maybe a day or two. If you want, you can shake it to dissolve CO2, but I'm lazy and just let time do its thing. It's awesome. So much less work than bottling.

Agreed, but I expect the HN audience is already far from the norm covered by your "many people".

https://www.madebybarb.com/2016/06/13/diy-home-carbonation/