in reply to XS, raspberry pi, and a hundred bucks
Thanks for buying the book! :)
Buy a Pi 3 and a NoIR Camera Board v2. Make sure you've got a 2.1A USB charger plug with a good quality cable. You'll also need a good micro SD card. Mine all range from 16-64GB. Spend a little more here; a quality card makes a difference. All in all, you should be right there in around $100.
I learned XS over time and don't remember the reading I did. WiringPi, which is the backend to RPi::WiringPi which the Raspberry Pi book is based on is an XS module. Most of the code wraps an external C/C++ library, but there is some XS involved. A very trivial XS module I've written is Bit::Manip. There's not much XS there either, but it's a good example of how to present C functions to Perl code, how the files all hang together and such.