> I would expect around 50k-60k for a 1000 sq ft roof (not US).

That's about 90 m². Here in Germany [1], if it's just replacing tiles, you're looking at 10k, add 20k for adding heat insulation - and you can get 15-20% back with government assistance from that sum. The only way you reach 50k in costs here is if you have to fix structural issues (e.g. rotting wood due to water ingress, but if you take proper care of your roof you won't need to do that - expected life time for roofs is about 80 years for the tiles and much more to the tune of centuries for the wood framing.

[1] https://www.obi.de/magazin/energiesparen/daemmung/dachdaemmu...