You can buy stabilizer in 4 lbs bottles in Walmart. I’ve also bought it from Amazon.
The problem with pucks is that it’s very easy for your CYA to get too high. If your CYA is at least 30, and If you stay on top of it and switch to liquid chlorine as soon as it hits 50, and change your target FC as the CYA goes up, it isn’t wrong to use pucks.