Once your books are completed, if you come back to us later, and tell us (as many authors do!) that your readers found typos, and you'd like to fix them, we'll make those edits for you at the same going rate as our usual edits, plus a $25.00-$50.00 book production fee per title (not per ebook format) for remaking the books. The price depends on how long it's been completed (things can change dramatically in the eBook world over, say, the course of a year!). We charge the remaking fee because unlike MS Word, edits in ebooks aren't as simple as changing a typo and hitting "save;" we have to do a fair amount of work to edit an epub, save it, make certain tweaks to use it for generating a Kindle book and then making the matching Kindle version. We're not out to gouge anyone...but even the smallest change takes time to revamp into both book formats, plus administrative and overhead. A Kindle book (a .mobi file) is actually a binary database file that must be built from its HTML source, every time a change is made, no matter how small. Unfortunately, this takes some time, so we have to charge to cover our costs.
We highly recommend that you save up those ubiquitous reader edits for at least six months, so that you get the most "bang for your buck."