Good and real cheap may not be possible. I advise being as fussy about your pfds as you are about your canoe and paddle. Too often pfds (and wearing them) are an after-thought
I’ve been paddling a lot for 14 years or so. Early on, I got cheap pfds and they were pretty uncomfortable. About 10 years ago, someone—maybe it was here at the forum, or an Assembly—said many professional guides use Seda pfds. I got some from Piragis (Boundary Waters Catalogue) and have been 100% happy with them ever since. My daughters wear them when they paddle with me and have no complaints about fit. They’re constructed of a large number of vertical pockets filled with floatation, have a strong zipper, waist ties, and two large Velcro flapped pockets. I never know I’m wearing one when I’m paddling, except maybe when it’s kind of hot.
Start with the best you can get: it’s cheaper in the long run. You’ll wear it if it’s a good one and that makes all the difference.
Very often the attitude I encounter among casual paddlers is, “if I’m wearing a pfd, it indicates that I don’t have confidence in my skills.” I take the opposite view. Paddlers who don’t wear pfds are advertising their incompetence. Good paddlers know accidents can happen anywhere anytime to the best paddler and it’s a courtesy to other paddlers who may get involved in rescuing you to have the pfd on.
True story. My first paddle this spring I encountered a kayaker on the river. Top of the line kayak and paddle, but paddling sans shirt and pfd. Now it was a warm day but there was still ice in the backwaters so think of what the water temp was.