Going by the wishlists I (fortunately) saved to my own computer before the mess started, and then comparing them with prices now, the most increase I have seen on a previously released title is $1.00. However, prices on four books that have been on my wishlist forever, simply because I thought they were priced too high, have come down in price considerably.
What will be increasing is new releases, from $9.99 to $12.99 or $14.99. That is, once they're available again anyway (don't get me started, there's a ton of stuff being released tomorrow that is now no longer available in ebook due to this crap). And that is for books being released in hardback, not those being released in paperback. I see new releases in paperback going from six and seven dollars up to $9.99, though, and that one does hurt a bit.