Price is always relative.
I'll happily spend £10-15 on a new bluray, spend £5 on munchies, and then hesitate at spending 69p on a mobile game or app that looks interesting. Yet much more time/effort went into creating those apps and games than the £5 worth of munchies that I'd get a few minutes of enjoyment out of vs hours from the app/game. It's not rational, it's not logical, it just is
Some people will have a similar feeling about ebooks.
As for the coffee, I consider most coffee places over priced and won't use them. Only time i'll buy tea/coffee when I'm out if it's as part of a lunch, at which point the cost doesn't seem to be as big an issue then.