PicMicrochips are cheap and easy to work with but you first have to decide what type of sensor do you want to use to tell you your altitude? And what type of value does it output?
High-g shock accelerometers might work
Here is a cheap programmer that works with a lot of pics:
http://www.picbasic.co.uk/forum/arch...php/t-703.html
It uses the IC-Prog software.
http://www.ic-prog.com
You could order a sample pack form the Microchip website(might want to buy 1 or 2 for faster shipping). The 28 pin 18F2580 should be more than enough to do the job. It has the software processing capability of the FRC controllers(at 40 Mhz). It just doesn't have as many hardware features. 18F4520 and 18F2480 are just as capable. 18f4520 is the easier to work with but but it is bigger with 40 pins.
This sensor might work: Motorola MPX4115A(pressure sensor)
http://geocities.com/SiliconValley/O...33/MPX4115.pdf
http://www.geocities.com/SiliconVall...altimeter.html
Try to figure out the voltage to pressure ratio.