The story of diapers.com is probably as clear cut an example of predatory pricing as you could get:

https://slate.com/technology/2013/10/amazon-book-how-jeff-be...

The whole point of predatory pricing is that you jack the price up if you don't currently face any competition and use the threat of plunging prices to scare off competitors, so of course they're going to be more expensive by default.