Those are getting kinda long in the tooth. you'd have to see it.
Lenses you can get, lens boards or mounts are a little tougher,
film carriages can be a tough to find and cost way more than $50.
Like many color enlargers, the chromega's have filters that fade over time.
Depending on it's age, these could be unreliable for setting contrast on b&w images.
Someone selling just the head would probably want a lot more than that if it were in good shape.
The one's I like for 4x5 [kind of in this order]: saunders/lpl, durst, devere, omega...
Good enlargers, along with all the holders, lenses and lens boards, power supplies, etc, are hard to come by and can still cost a bit.
I'd say keep looking, you'll spend a lot of time around the one you get, and you want them to be bombproof, and have very few issues
so you can concentrate on the important stuff, like making art
-Tim