Since you put family in there.....I believe you have to be 16 for one of those you posted a link to, I believe there is also a weight requirement too.
Of course everyone wants to buy quality but cost does enter the equation even if we do not want to admit it. I wore one of the inflatable types when I bass fished for years but have since went back to the a quality foam PFD...it never fails. Teaching kids to swim at an early age for me is huge, I am shocked at the number of kids now days that can not swim.