I read through the whole course and now starting over and this type actually building stuff.
I was wondering about the servos, I live in Canada and the link you sent shows the servos at 16USD, I'm considering these servos here: http://www.robotshop.com/ca/en/hitec-hs422-servo-m... (not affiliated with them) from a Canadian shop at 12$(CAD) which is much cheaper, but I have no idea if I can modify the PCB and it doesn't say if it's a DC servo anywhere on the page.. Are the servos all usually made the same? Anoter alternative is Aliexpress but it's going to take ages.
Can you think of any other stores by any chance? Wish instructables sold the stuff themselves