Regarding pricing: I wish we could price it much lower but the reality is that this tool is extremely niche. We've also put a _huge_ amount of work into it and I hope it shows in the amount of polish (although there are many more things we would like to improve and add but we had to call v1 at some point). If we ever stand a chance to continue making the best software we can, we have to price it in such a way that will allow us to do that. Note that we might still fail and not achieve a sustainable level but if we priced it at, say, $30 or $20 then we would definitely not be able to continue making the apps we want.
Regarding 10.9+ requirement: we do depend on the improvements in AppKit in 10.9 regarding layer-backed views and hence the requirement.
I understand the reasoning, but I was going to purchase it, then saw the price, £39.99. I'd probably have bought it at £20, but for an app I'm not going to use very often £40 is too much for me.
Stick with the pricing. The application is niche, and as such should have a higher price. It has been noted many times over that software has a bimodal pricing scheme - very cheap for off the shelf software, and very expensive for bespoke software. But of course, that's the black and white view of the world. The more 'niche' your off-the-shelf software is, the closer it gets to being bespoke, and the price should rise accordingly. It works in the other direction as well of course - if you can build an application by simply tweaking an existing framework, such as building a website using Squarespace, then this should cost much less than true bespoke software.
All of which is to say that I feel that you have the right approach to software pricing. I hadn't realized this exists, but I may well become a customer in the next few days - I have been looking at options for creating UML documents in code.
One thing though, do you have a re-import feature? This is the killer feature for me - I would love to be able to create a URL diagram in your app, paste it into the top of a source file, and then copy it from the source file back into the app for modification later when the code changes. I realize that this is a tricky problem to solve, but solving it takes this from being a toy to being a true industrial tool from my perspective.
I understand your justification for the pricing but you need to be wary you don't lose too many sales by pricing too high, and $65 is too high for a casual "use it once in a while" purchase for most people. Maybe you could have multiple pricing tiers such as a "Pro" version that has flowcharting tools and such? Then you could drop the price of the "Basic" version to something people are a bit more likely to purchase as an impulse buy...
