Cost to Repair Rotting Beams in 1840s Log Home

I am looking to go to an auction on a log home that was added onto in the 1990s. The original home was built in 1840 and the beams in the basement seemed to be rotting and once had a termite problem. I was wondering roughly what the cost would be to take care of these rotting beams and if they needed to be replaced, what that would look like?

Thanks