Hi, I might be buying a used t400 that doesn't work. It had water spilled on it, no more information other than that.
The indicator lights for battery and AC still turn on when plugged in.

What are the most likely things to be damaged/ruined?

Count on replacing the motherboard at the very least.

Unless you're getting it for free or very close to it, it's probably not worth the time and $$$ involved.

I was hoping to use it for parts, but I'm told the 128GB SSD and RAM are fine(?). Without the SSD would $100-125 be a fair price?

I would doubt that anything is fine unless the seller could prove it to me...water damage is nasty.

My top offer would be no more than $50.