It's perfectly fine to consult an expert as long as you pay them for their time and expertise.
The best beta reader for your book is one who's primed to love it, and who can work with you to make it the best possible book on its own terms.
Asking beta readers to start reading, finish reading, and talk to you about what they read doesn't seem like a lot, but it can feel pretty daunting from the other side.
Critiques should not make you question the value of your work, or the value of yourself.
I love the idea of a beta reader dating service! And in fact such things exist.