Believe it or not, that's not even for calculators. Those are surveying pac add-ons. They're like memory cards that contain programs specific to surveying.

They come up on eBay, but the bidding war thing gets old, and unless you're willing to bid really high, you have to wait quite a while to get one reasonable. They go for $60-$80 at times, and then they'll all go for $200 for a week or something. Kind of nuts.