There was a while where this thread got a lot more traffic, but it's slowed down. The publishers seemed to play more with prices than they do now and the books that are on sale seem to be the old ones in rotation.
The Tecarta app has a few study Bibles
on sale right now, but they're still pretty expensive ($14.99 instead of $19.99). They had good sales early on and I was able to buy a bunch with Amazon coins, but the study Bibles are now more expensive than buying regular ebooks. I did add the RSV, NRSV and most recently the new CSB, but I haven't sprung for more study Bibles.
I like the app enough, though, that I run it in an Android virtual machine on my desktop.