Mike from Conyers, GA asked me this question a few weeks ago. I gave him my accountant’s answer: “It depends.”
Well, to self-publish a fiction or non-fiction book, you need an ISBN and barcode from here. That’s $125 for the ISBN and $25 for the barcode. If anyone offers to sell you an ISBN for less than $125, it means they will be listed as your publisher, not you.
For editors, I recommend going here and looking for someone who knows Oxford style. The lowest I’ve seen for an editor is $2 a page. The highest? Just above $4. Make sure they know what they’re doing. This is not a place you want to cut corners.
My cover designer charges $105 for e-books and $160 for full covers and the interior designer I use charges $60 an hour. For a cleanly-formatted fiction book with little interior art aside from chapter breaks, that would be about $100. Honestly, both of those are way below the industry standard for design, but if you find good people for less, stick with them!
Lightning Source, which prints most POD publishers’ books, charges $70 to set up a new title (text and cover).
So, for a 250-page book with $2 a page editing, I’d pay just under $1,000 and retain all rights with no fluff. If you pay more than that, I’d really ask the POD publisher where exactly it’s going.