I just purchased quite a few pen kits at WC today and I'll tell you 2 reasons why.
Some of their kit prices are ridiculous, but some are pretty close to comparable and with the discount are cheaper then similar kits online. Plus I don't have to pay for shipping, nor do I have to wait. Those are just benefits, not my reasons.
Reason one is I want to keep my Woodcraft in the area. I've spend plenty at Exoticblanks, Beartoothwoods, ArizonaSilhouette and Woodturningz over the last year.
Reason two is that I find I do not have to replace the ballpoint refills of the kits I purchase at woodcraft. I don't care if it's a PSI product or a BereaHardwood product from one of the online vendors I've already mentioned, I must replace the refills. That will reduce my cost further.