@Glen Wheeler – I think you should first decide what you want from the editor. Do you want an overview of your book, i.e. does the structure work, are there plot holes you haven't noticed, is the dialogue realistic or wooden, are the characters one-dimensional or do they leap off the page, grab readers by the throat and pull us into their story? An assessment of your work is quite different to an edit, and some companies might take your money, edit the work so it reads okay grammatically, but not mention that chapter two is completely superfluous to the plot, Characters E and G don't actually work, and there is no real underlying story... you get my drift
I think hiring a good editor at the right time is a good idea (there are a lot of amateurs who think it doesn't matter if their work is sloppy or incomplete, that the agent or publisher will sort it. No, they won't. They'll just bin it). But please don't even think of paying money to anyone until you have gone through your work as much as you can to ensure it's as polished and tight as it can be. There is no point hiring an editor to edit your work if it isn't 'there' yet. You'd be much better putting it up on the Writing forum here and asking for Beta readers who might save you a lot of time and money just by letting you know what works and what doesn't. Yes, you might get conflicting advice (that's not unusual), but you'd be able to sift through that and see where people agreed. If everyone says you need to cut and tighten dialogue, for example, then you need to cut and tighten dialogue... if they all think there's too much flowery description, there's probably too much flowery description. And if they all love the premise – you know you're at least on the right path.
I'm concerned that someone says they charge per page... is that double spacing per page or single spacing? What kind of margins? Anything that's vague should ring alarm bells for you. Find out exactly what you get for an exact word count, and how long they're going to take to return your work. Check if they know the difference between a proofread and a line edit... but first, familiarise yourself a bit with editing terminology, and shop around. Forewarned is – you know!
But I would definitely check out the writing forum on here first.
Good luck!
