I also had "invisalign" before it was called that, when I got my braces taken off quite a few years ago.
Not sure of the cost-but the commercials say you can wear them all day and it's not noticeable...well...if they still make them the same way, you will most likely have a lisp while wearing them, and you CAN see them on. It is possible they make them thinner now-this is just my experience. I only wear them at night.