You should get a beta reader or two who aren't writers so they can tell you more objectively if your book appeals as far as story and the things most readers care about. You'll often find you get vastly different feedback from writers and non-writers--both can be valuable, but often the pure reader feedback is a bit moreso.
I don't remember if there are rules about suggesting actual people or not, so I'll err on the side of caution. But if you Google "your genre editor" you'll find a great deal. Just then google the editors names to find where they're discussed on messages boards and such. Look at the books they claim to have edited. Maybe reach out to people who've used them and ask if they'd recommend them.
Vet them the way you would anyone you pay for a service. You're probably going to pay at least $500 or more, depending on the length, and that's kind of a bottom barrel number. A bad editor is worse than none at all, so really shop around.
Yes, it's pricey, but if you spend $150 on a budget one willing to do a full novel at that, how many hours do you think the editor can reasonably spend and make any money for the time? I'd be afraid of a rushed job and a waste of that money.
If you get some truly excellent betas that can help you whip it into shape, you may be able to get away with only proofreading. A lot depends on where you are in writing and how much experience you have--and how good your betas are.