Why is it hard to increase the price? Is it harder on the app store than anywhere else? Is there a way to track the price history of apps, or is there a website that does? I'd love to know, I'm considering making an (expensive) app and pricing is a hard problem for any software product.

Because the users will notice and start slagging you in reviews.

Yeah but that's true for any market. Is there data that indicates that this happens more for appstore software? I mean I'm not asking for a peer reviewed, 1000 apps study or anything, just a plausible indication that the average appstore customer is more likely to do this and/or be influenced by blog posts complaining about price hikes. Maybe just showing that appstore customers are far above average in being likely to read and be influenced by online reviews is enough - if there is some correlation to be made between appstore customer profile and sensitivity to price hikes.

It's not true for every market that customer reviews are prominently featured at the sole point of sale and can immediately reflect reaction to prices set directly by the developer. That combination is pretty unique to the app store right now.