Used custom forks aren't the best idea
Unless your riding style, size, and intended application (not to mention frame geometry) closely match those of the seller, you should steer clear. A custom fork built for someone else may be TOTALLY inappropriate for you, and the consequences of a fork failure can be pretty ugly.
In general, I don't understand why people buy used custom frames or forks that were made for someone else - I mean, honestly, you're better off buying a new production frame instead. It's going to be just as cheap or cheaper than a used custom, you can find a size that will fit just as well, since the custom frame/fork wasn't made for you, and it'll be under warranty if you break it. A used custom bike is a bad investment unless you *really* do your homework and are dealing with a trustworthy seller.
Just as an example, I once built a custom fork for a 130 pound racer who wanted it as light as possible - full on tricked out fork, with a custom machined crown, ultra lightweight blades, etc, etc. Then a year later, someone I've never heard of calls me and says he broke one of my forks. Turns out the 130 pound XC guy sold the fork to a 220 pound dude, "in good faith". While I'm sure that the fork was fine when it was sold, it was also totally inappropriate for the 220# guy, yet that thought never crossed the the buyer or seller's mind, apparently.
So call Rick and have him build YOU a fork. You'll be much better off, and saving a couple of bucks buying someone's random used fork might not pay off in the long run.