I don't think it's a question of right or wrong.
In general, I personally think the e-book version should be a little cheaper than the print version. But realistically, I'll pay the paperback price (if it's out in PB) to get the ebook--I'm out of space to store DTBs, and it's nearly impossible for me to get rid of them--I rarely loan books because I never get them back, don't swap them because I re-read, etc.
Worse than that, I'll probably spend more to get the book sooner if it's not out in paperback yet. While I rarely, if ever, buy hardcovers anymore, the Kindle version of a new hardcover is invariably more than I would spend on the paperback. And while I'll wait for it to get down to $9.99 typically, I'm not waiting until the paperback release anymore. LOL So I'm actually spending more for new releases than I did previously.
But I didn't get into ebooks expecting to save money. The amazing number of free & bargain books is a huge plus, obviously, and I'm taking advantage of it, but I knew going into this that I would be spending as much, if not more, to feed my reading habits.