I reckon it's quality not quantity. You could have 1000 junk names and not be a "domainer" (because you're never realistically going to be able to make a living in the industry on those names i.e. they're just a portfolio of broken dreams) or you could have 50 top, really eye-opening names and be a domainer.
But realistically if the quality's there, once you start getting into the "few hundred" you're probably on the way to domainerhood/domainerdom/?