Ok, so a bit of response:
First, you can hit the $30-$50 mark if you add up accommodations also. I've done the Cabot Trail, parts of NS and the eastern half of PEI. It's a lot more settled than most people would have you believe so you're more than likely going to be paying for accommodations.
Second, the Doers and Dreamers' guide is excellent.
Third, for Cabot Trail, it's recommended to do it clockwise. I also think it would be better to do the eastern half of PEI clockwise since we encountered some stiffish winds along the north coast there.
Fourth, you cannot take your bike on the Confederation Bridge between NB and PEI. There is a free shuttle service consisting of a pickup truck with racks on it. Make sure to strap everything down because the crossing is VERY windy.