In the case of Connie Shelton at least, she's one of those previously-established authors who's switched over to self-pubbing her former print backlist and releasing her newer works herself via CreateSpace.
Here's a listing for an old
mass-market paperback copy of one of her books in said Charlie Parker series, published 1998 by a small press. And she's apparently included in this
Chicken Soup for the Writer's Soul collection from 2000.
Disclaimer: I do not know and have no association with this author, beyond having downloaded a couple of her books free from Smashwords during the Read an E-Book Week promotion. I have not gotten around to reading them yet and cannot speak as to their quality or lack thereof.
And while I wouldn't dismiss self-published work out of hand if it looked interesting, I do consider it a greater deal when it's a regularly-published and priced title that's discounted for whatever reason.
Even though I'm never tempted to buy any of these things, it just looks like more of a "bargain" to see something that one of the major imprints has knocked down from 9.99 to 2.99 in an attempt to get it to move, then to see an indie work which seems to be starting at the same price for the same reasons.