Tantor Media is having a sale that they're calling "New Year New Series." They have 522 books, which are the firsts in a series, that they are offering for
$6.99.
With these being the firsts in a series only, don't expect to find any non-fiction books among the selection (popular fiction books are in series much more commonly than popular non-fiction books). They'll almost certainly all be fiction.
This sale is good for the rest of this month.
I consider
$6.99 each a pretty good price for decent audio downloads, although I've certainly gotten spoiled to rock-bottom prices because of the likes of Audible Daily Deals and Whispersync deals.
Here's
a link to the beginning sales webpage for you.