Modolo Kronos
 

I'm looking for a rubber boot/cover for a single Modolo Kornos brake. Modolo part # M0027 Super rare but somebody has one somewhere.

I think they dry rot just as much as typical latex rubber brake lever hoods do, so they just get more scarce and expensive as the years go by.......
Most used Kronos calipers that you see out there on bikes have some sort of dry rot issues, with their caliper covers. Only the NOS ones are usually the ones that look good.
If only they made them from silicone rubber based material, the would not be so hard to find in good condition.

still looking? i have some

Yes, those Kronos caliper hoods are pretty much unobtanium, these days. Plus, you'd pay big time if you find one in decent condition, if you can even find one. I haven't noticed any good Kronos brakeset stuff for sale out there, for a long long time already. Mostly just the brake levers, and most of them are trashed already.
If you have a good one to use as a pattern. Maybe you might consider molding them yourself in silicone rubber, if you might be up to it?
If you check around, there are lots of molding kits available for hobbyists.