Rickys are pretty rare anywhere and everywhere, but especially so the 4004's. It was bad enough tracking down a 4003, and that's supposed to be the 'standard' model. I'm kinda in two minds regarding the Cheyenne. On their own merits, I quite like them, but they have am excessive price-tag, and when it comes down to it, I just prefer the 4001/3 looks...
On the other hand, considering the rarity, if you've found one, go for it!