For now, as mentioned in the post, – in retrospect – I think that in-app-purchase was not the best approach for the Economy app. I can add that I haven’t yet found any developers who implemented IAP in paid apps and were happy about their numbers, but so far, I only know of three other developers who’ve implemented IAP in paid apps.
Btw though I’m not ready to write the IAP blog post yet, I’ll be happy to talk more about my current thoughts if you email me.

My suggestion that “A $1.99 price may increase the revenue of most good $0.99 apps” was somewhat speculative and also balanced in the same paragraph when I said that an increased price will be accompanied by reduced volume and that this will further reduce sales because of the resultant reduced visibility. I’m sure that the results will be different for different types of apps. However, it is very interesting to know that revenues stayed the same in your experiments (and that of your friend). This is very good data and tempers my speculation a bit.
I also agree with your other comments on why price changing might be a good idea.

On your other comment, I did think a lot about the visual design of the Economy app, but I hadn’t specifically thought about it in a pricing context. However, you’re correct in suggesting that the visual design plays a big role in the “perception of worth”.

You’re right in pointing out that pricing discussions should first talk about “the target audience”.The post talks about market segmentation to address the “money on the table” problem (which you’re referring to as surplus value), but a developer has to know who his/her customers may be before dividing the market into groups of (potential) customers (i.e. market segments).

I question your assumption that increasing price increases revenue – about a year ago I have conducted a few experiments and revenue stays flat except for one-day bump you get on the day of the increase. Same holds true for decreasing prices and results were repeated by a friend of mine. All tested apps were “productivity” (my own Memengo Wallet and friend’s To-Do kind of app). Having said that, there are some valid reasons to change the price:
1. Manage tech support / feedback channel saturation.
2. Keep away low-quality users: the lower the price the more youtube-style one-star review you will get.
3. Get a shot at moving into top X by volume, which may have benefits.
4. Price movement could attract attention by themselves. There is a number of sites that are watching “sale” events and they probably have audience that reacts to the sales. Sadly there is no way to measure this.

There are two subjects I think are wroth your further attention 1) capturing surplus value – you are already down that path and you will find a lot there 2) impact of visual design on the perception of worth. You did a thorough job at visual design in your finance app, however you have neglected to mention how conscious you are about that in your study.

Lastly, no talk about pricing is complete without thorough discussion about the target audience of your app. I am mostly oblivious about who are my customers and that’s the most worrisome problem I face.