Perhaps I should have noted in the original post that $10 is consistent with other jailbreak applications (BiteSMS, Intelliscreen), which seem to generally cost more due to significantly lower volume than appstore apps. It's also a small price to pay (to an independent developer, no less) compared to other accessories you may have bought with your car (floormats for $150, trunkmat for $75, a net for your trunk for $115...)
Anyway, I was getting into app development to earn a few more bucks to pay off 100k of student loans. I wanted to do something creative, but it sounds like I'm better off in the high volume appstore.
As for the quality of other jailbroken apps... I had Intelliscreen and paid $10 for it. I also had BiteSMS. Both applications had a high level of visual polish, but one or both of them contributed to a noticeable slowdown in phone responsiveness.