One month ago, I ordered an HP 15c Limited Edition calculator from HP's website. I wasn't actively paying attention to the fact that there was a re-issue of the 15c. I just happened to remember a high school friend who had one (back in the 80's), thought about how I always wanted one, and went to the HP site to see what they had. I saw the 15c Limited Edition and decided to order it.
A week later, they apparently ran out, since it disappeared off their store. I don't think they are scarce though, since a few quick searches still show plenty of them for sale from other vendors.
There are many interesting sites about HP calculators and the 15c. Eddie's Math and Calculator Blog has a series of posts on the 15c. The Calculator Store has a page with interesting links. The Museum of HP Calculators has all sorts of information and forum posts about HP calculators.
There a quite a few passionate HP calculator fans out there, and it's easy to see why: they are beautiful, well designed, and well made devices. I've enjoyed reading through the manual, learning about RPN and the stack, and the various clever ideas they used to put so much functionality into a calculator 30 years ago. Although the Limited Edition has a newer and faster processor, they kept everything else the same: * 448 bytes of memory * 67 storage registers (by default 21 for data storage and 46 used for things like imaginary numbers, matrices, programming, and other things) * a 4-level stack calculation stack : x, y, z, and t
That doesn't sound like much, but it's amazing how much the 15c can do. Imaginary numbers are fully supported (using a parallel x y z t stack). Many matrix operations are implemented, and the interface for entering and manipulating the matrices is quite usable (once you learn it). Programming, although definitely from a different era, is still powerful and straight forward.
It's too bad I never purchased one of these during my school years. It would have made using a calculator so much more fun and interesting.