A few of Erle Stanley Gardner’s classic Perry Mason books have been recently re-pubbed in e-book, with new covers, by Mysterious Press/Open Road – probably due to the HBO series. Mostly these go on sale for $1.99 or $2.99, but now here is The Case of the Green-Eyed Sister on sale at Kindle and Kobo US for $0.99, and it’s discountable at Kobo. It’s also on sale for £0.99 in the UK, which is even rarer, since Mysterious Press/Open Road titles don’t go on sale much there.
The Case of the Lonely Heiress is a bit more than 1/4 of the way through the Perry Mason series. (Don’t believe the webpage, which says it’s the second in the series – that numbering refers only to the ones that have been recently e-pubbed by Mysterious Press/Open Road, and those are a tiny fraction of the series.) It has dropped to $1.99 at Kindle US today: https://www.amazon.com/dp/B084TLTM17