I'm not quite sure what would have caused that. Maybe having a fluted seatpost installed way to deep, and getting a pebble down in the flutes, then twisting HARD?

Do you have a brand for the frame? What caught your eye about it?

I have a mixed opinion. If it was my own bike, I might braze it, or ride it as is.

I'd probably select a seatpost that would extend a few inches below the damaged area. Make sure a standard seatpost fits.

Buying it? I'm not sure. I enjoy "projects", but expect them to be CHEAP.