Enco has their own brand (Chiwandian, I'm sure) drill chuck arbor for
$4.22 & a Jacobs brand one for $17.75. I'm assuming that there is a
difference in quality, specifically runout, but is the Jacobs one 4x
better? For use in a drill press (not lathe tailstock), do you think
the "Enco" one would be acceptable?

The arbors:
http://tinyurl.com/6aog3g
http://tinyurl.com/6qed79

(Ummm ... the price on the catalog page is $4.22, but ordered it's $4.44.)

Bob