Looks awesome! I guess my only concern is $65 AUD seems a bit high? Also, is there a specific reason why it needs 10.9+?
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.
Hope that clarifies both issues.
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.