I went to home depot today, to see if they carried Dichlor. Leslie's carries dichlor at $36 for 8lbs. Home Depot does not carry Dichlor. Instead, you can buy trichlor tabs, 3", 1", and trichlor "shock" granuals which includes fun additives such as Boron (borax?) and some clarifier. The 1" 5lb pack of trichlor is $22.50.
Since cyanuric acid clearly isn't doing it for me in my pool, I have decided to add CYA through stabilized chlorine. I have yet to see someone cause themselves problems by adding CYA, but I see people getting into trouble all the time with stabilized chlorine. So stabilized chlorine it is. So do I use trichlor or dichlor. I had always thought of using dichlor because it puts in .9ppm CYA for each 1ppm FC. However, if I play with the spreadsheet, I find I actually get more CYA for 80oz of trichlor than I do for 80oz of dichlor, and a heck of a lot more FC. So for $22.50, I should get 40FC and 22CYA from trichlor. And with 64oz of CYA for $20, I should get 32ppm CYA, but I actually got 10ppm CYA. It seems to me that trichlor is the best deal I can find (though pure CYA would be better if I could find a reliable source).
Now, Home Depot does sell CYA at 80oz for $18, I have just learned. It is certainly not Leslies, but the packaging does not even attempt to guess at how much ppm CYA I would get for any amount added. All it says is to add some if you are below 40ppm CYA and retest. I have this funny feeling that the purity of 100% cyanuric acid has a lot of variability. However, attached to chlorine in the form of dichlor or trichlor, it seems quite reliably potent. I'll know for sure as I start using my trichlor tabs.