A week ago I posted a list of several self-pubbed books I'd enjoyed. One series, by K. T. Davies, currently has the prequel novella up on a few giveaways. You have to sign up to the author's mailing list to receive them, but Davies only emails once a month, if that, and it's not like you can't unsubscribe. :) The links go to the giveaways, and they randomly shuffle the positions of the books, IIRC, so you'll have to look for the title.

The Best Laid Plans In this giveaway and also this giveaway.

If you've got Kindle Unlimited, Dangerous to Know, the first book in the series is there, and it's also $ .99 if you do't do KU.