Started Early, Took My Dog - Ebook prices

I've had a Sony ebook reader for a while now and have used it quite a lot for free books and review copies. I haven't bought many books as it seems ludicrous to pay lots more for an electronic copy than a paper copy, so I'm very pleased that WH Smiths have reduced their prices by 50%.

I thought I'd illustrate the range of prices for the same ebook with Kate Atkinson's Started Early, Took My Dog which has just been published.

Print RRP = £18.99
Epub RRP = £19.40

Amazon Print: £8.16
Amazon Kindle: 5.71

Bookdepository Print: £12.51
Bookdepository Epub; £14.55

Waterstones Print: £8.99
Waterstones Epub: £18.23

WH Smiths Print: £8.99
WH Smiths Epub: £9.70

The cheapest Epub version (of this title) I've found is at Kobo at £5.71 and they are currently offering £1 off all ebooks this weekend if you use the discount code smashing1.