Eerdmans is having a big sale on what one website describes as "Academic/Theology" ebooks.
There are lots of ebooks on that subject, published by Eerdmans, that are available at Amazon, and they are at truly fantastic prices--some are as low as
99 cents (however, a couple of them are widely available reprints of works by Louis Berkhof). A large number of them are priced at
$1.99. Then, there are a good number at at the
$2.51 (yes, that's
$2.51--I don't know why that figure was selected). The next price point seems to be
$2.99, and there seems to be a large number of titles for that price. For you spendthrifts (

), there may be some higher price points--it seems that I saw several at the
$4.99 price point, for instance.
I suggest that you go to the
Amazon website and do a search of Kindle ebooks using "eerdmans" (without the quotes), "eerdmans" (with the quotes (some astute MobileReader pointed out the fact that enclosing the word within quotes can yield some additional hits)) as the search terms. You might try doing the same thing using "Wm. B. Eeerdmans".
For a company that has its act together in so many ways, Amazon can't seem to create a "sort by" function that yields accurate results--at least not for the "low to high price" choice. But using that is still your best bet in order to ferret out the best deals, IMHO.
My super-secret sources

tell me that the sale lasts through April 30, but sales like this have been known to end early.