I was checking out e-gobooks where you could previously get all the Japanese weekly and monthly go magazines. Nihon Kiin has started to add previously published books like Iyama's self commented games and the Heart of Go series. Many books appear to be listed for half the price of retail paperback.

So far I've tested it on PC and Nexus 10 and the books work very well. I'd guess iPad would be fine as well, since it's all browser based.

https://e-gobooks.nihonkiin.or.jp/

I see they are marketing Kobayashi Koichi's three volumes of Igo Hissho Koza. These are fine books. I'm glad to see they are still available.