Definitely not unreasonable, Frank. However, you have a couple of options. Rather than pay for a full developmental edit on what you have written so far, you can ask the editor to do a manuscript assessment – which includes a detailed written report. An MA is usually done for a fixed price based on the word count. Alternatively, you could ask the editor to do a sample/developmental edit on one chapter only. Using track changes, they can go through and make edits and comments. It’s good that you are already thinking of hiring an editor before you complete the MS. It will help guide you with the other 40% and revisit what you’ve written so far, so that once you are finished, the MS will be in much better shape for the next stage of editing.

“My books have very complicated formatting with over 100 illustrations each, external links, and numerous bulleted lists. None of the formatters I contacted would even take these on but John said “No problem!” He completed my original three e-books quickly, for a more than fair price, and they look great. I have no hesitation recommending Ebook Launch’s work to other e-book authors!”
For editors who are charging pennies for what should be hours and hours and hours worth of work: I am saddened that you would ruin the market for those who have the expertise and ability to charge what it’s worth. You see, an author whose book needs a whole lot of help will see your rock-bottom prices and think that’s the norm. But the reality? That’s not normal. It’s not normal to charge sweat shop rates for something that requires top-notch quality.
I was referred to Ebooklaunch by another author friend, after searching for the perfect cover and layout artist. I was about to give up, but once we emailed back and forth and I gave them the concept of what I had in mind, I thought I had nothing to lose. I was astounded by the design, for: Case of the Mouse Trap Legend. I was absolutely blown away - it far exceeded my expectations. I couldn't be more thrilled and will return in the future for more covers. Thank you very much!
It is not the best option. A program will never beat a good editor. The only thing I suggest is that a writer uses a program to help as they work or write. This helps make your book cleaner and causes less effort on the editor – making them happy and if done well enough, could cause your rates with the editor to stay lower or low. If you have too many issues, an editor may demand more.But if you just cannot afford an editor, then the best way is to use a program, and have you do a full read through, and have someone else (friend) do a full read through…and the more the merrier.
I am not without sympathy when some new authors get “sticker shock” upon hearing an estimate for my editorial services, and I am actually relatively affordable. (Most reasonably well-written novels would not cost even close to $3000 for me to edit, let alone $5000.) I also offer generous installment plans and discounts for bundled services. But there is a limit to how low I can go.

If however the editor is going to disassemble the book act by act, scene by scene, beat by beat, and show technically in story structure terms what needs to be changed, then the editor is spending far more time in analysis and constructing the demonstration of such to the client. Of course, this really depends on what service a client wants as well.
You might hire someone for a proofread, but let the editor know that you’re open to hearing from him or her if the work needs a heavier edit. The editor would need to present you with evidence in the form of sample pages that showcase what’s needed—and your job is to make sure you agree. You want to feel like an editor’s edits are polishing your work and making it shine. If you feel dread or anger, or even if you feel misunderstood, it’s likely not a good fit. At the very least you want to share your reactions with the editor so they can respond or change course.
I used Ebook Launch to format my first book, a novella entitled His or Her Betrayal for both ebook and print, and I was happy with my results. They are very professional and get the work done in the amount of time that they tell you. I just submitted my second book Love, Lies and Heartbreak, which is a collection of short-stories for them to format for print and ebook as well. I'm sure I won't be disappointed in their work. They are my permanent source for formatting my books. Thanks so much for your great work guys!!
Blake, that’s wonderful info. Thank you. I completely understand the response about guaranteeing the work. That was just something that popped in my head as I read a book written by a screenplay consultant I hired years ago and he wanted a review so I read it to help him out but found maybe 5 or 6 error’s myself in the 200 page book. I felt like it was unprofessional but didn’t have the heart to tell him. But the errors stuck out like a sore thumb so I was curious if that is normal or not.