As Rancho Gordo is to beans, Masienda is to corn:
Masienda - masa supplies and ingredients
Started in 2014, they sell 15 varieties of Mexican landrace corn for masa, along with supplies.
As luck would have it, I recently gave away a never-used Indian wet grinder. I do have a commercial Vita-Prep blender, a Cuisinart food processor, and a Champion 2000 juice extractor with a nut butter mode. In another kitchen I have a long-discontinued Samap hand stone mill. I'm willing to buy either a metate and mano, or a Wonder Junior Deluxe+ Mill with masa auger (I distrust the less expensive equivalents). So I intend to figure something out, preferably stopping short of buying a Nixtamatic.
This is a classis "perfect is the enemy of the good" situation. The goal is to make the best tortillas one can eat all the time, not a once-in-a-lifetime bucket list cook like making potato chips. I'm reminded of grinding and extracting my own coconut milk. One has to source the right frozen coconut meat: Our fresh coconuts have insufficient fat, and frozen brands vary; country of origin is a good clue. Then extraction still doubles the work in a meal. The best Thai chefs I know, who cook Thai all the time, can't give up years of their lives to this, so they have definite preferences on which brand of canned coconut milk to use. There's something artificial about cooking Thai outside Thailand in any case; in Thailand one would go to the market and buy coconut milk from one vendor, paste from another, ... Canned coconut milk is not the same, just as masa harina is not fresh masa. Nevertheless, these cooks get to eat Thai all the time.
Prepping nixtamal is as easy as cooking beans from scratch. The crux move is grinding nixtamal into sufficiently fine masa. Here, I'm ready to place my bet that the winner is to grind wet in the Vita-Prep commercial blender, then thicken to the desired texture with masa harina, ideally something like Masienda sells. This is like cheating by adding white flour to whole wheat baked goods. Everyone does it.
I'll report back, after I've compared every approach I can, using various Masienda corn varieties.