Right now you can find the Dietrich Bonhoeffer Works, English Edition (DBWE, 16 volumes) for just $99.99 in Olive Tree Bible software. A few more Bonhoeffer items are also listed at their sale here.
Olive Tree’s iOS and desktop apps are free, so if you like Bonhoeffer and have the cash, this is probably the best price for his complete works in English that one will ever find. (It does not yet include the just-released-in-print Volume 17.)
Bonhoeffer died 70 years ago today.