At Tuesday's Apple Event, the original iPad mini (sans Retina display, of course) received a new, lower price tag of US$299 for the 16 GB WiFi model and a bit of a design update. The "black and slate" model is now officially the Space Gray model, and if you have your sights set on one of the re-packaged iPad minis, you should look no further than your local Apple Store. They're apparently showing up at stores, according to 9to5Mac.
You can also purchase the same low-cost iPad mini in a white and silver finish, and a T-Mobile version of the old, non-Retina iPad mini should be showing up around Halloween (cellular versions are available for all other carriers now). As for the new models with the Retina displays, they won't be arriving until sometime in November.
9to5Mac also notes that the Space Gray minis are not in every Apple Store at this time, so you should probably call ahead for availability information.