Pretty much the same as any enlarger, holes in the bellows, make sure the motor works, no missing teeth
on the drive gear. Head level on the track. I've seen one that the gear on one side somehow skipped a
tooth.
Are the lenses newer or older? Older are highly polished metal, (chrome or nickel) and somewill have odd mounting
threads. Newer one will be black and use a common mounting thread, usually 39mm, longer fl's may have larger.
Make sure it's got lens boards and negative carriers for the formats you're using,
B&W head make sure the condensers aren't scratched & lamp works, turn on/off, that's pretty much it.
For the color head, someone else should pop in & give a hand, I'm not conversant with them.
I'd think That $250 is reasonable and would include some accessories beyond what you've mentioned but that's my
inner cheapskate talking. Moving sale? Motivated seller.
The best thing is you can check it out in person and won't have to ship, that's a PITA