Will agree about never sending a critique with a submission (though I didn't think that was the question) and that good critiquers can give you at least as much great feedback.
That said, I would add that while an agent's or editor's paid critique can be either extremely helpful or extremely useless (it's still just one opinion), one is MUCH more likely to be helpful and worth the money after you have already worked on the piece AND revised it more than once based on crit partner feedback. And while I value CPs a lot, too, I have also found that editors and agents are usually more blunt and, more importantly, more focused on the most important issues in the ms. related to marketability (not just whether they like it or not, or whether it is "good" or not. Loads of good work dosen't sell, and there are lots of ms. that CPs like but that still aren't awesome enough to be marketable. And some CPs are much, much better than others, and the only way to know the difference is experience with them and comparing their feedback to professional feedback.
And then I'll add that no matter what, it's just one opinion, and editors and agents can only give that feedback from their own perspective. The work one agent thinks doesn't work at all and will never sell is the next agent's bestseller.