This calculator can do many things, and while a normal price is around $100, it can be found for less on some sites such as Amazon.
It can be programmed, and it has a spreadsheet. While it can link to a PC, it will not work with Windows Vista 64 bit, which is what I happen to have. The graphing function is cumbersome and cannot accept simple formulae such as the 2 wave EOT, however the spreadsheet does them with ease.
Here are some notes, and here are spreadsheets for the Almanac (EOT, declination, sunrise and set), the HD and VD sundial types.
The .XLS spreadsheet can be opened and used in Open Office (.ODS)
The notes have some ideas on how the Casio spreadsheet differs from Excel and Open Office, these notes can be very helpful.
PERSONAL PREFERENCE
In spite of the HP35s hype , my personal preference is the Casio fx9860, in particular, the spreadsheet, and its cost.