Smashwords (click link for a full list of participating ebooks) where you can get books on sale for 25, 50, 75 or even 100% off! Am I participating? You bet!
“DAISUKI.” - Enter coupon code REW50 for 50% off!
“HATSUKOI.” - Enter coupon code REW25 for 25% off!
“SEIKOU.” - Enter coupon code REW25 for 25% off!
Smashwords provides any format, including Kindle Mobi, Epub, and, yes, PDF. They even accept paypal instead of credit cards.