If you go back to the homepage, he's offering the plugin for commercial use for $37. I like this idea of monetizing the use of plugins, especially ones so well-built. (He's also offering direct support for $17, another interesting idea.)
$37 is a joke. I just purchased it b̶e̶f̶o̶r̶e̶ ̶h̶e̶ ̶r̶e̶a̶l̶i̶z̶e̶s̶ ̶h̶e̶ ̶c̶o̶u̶l̶d̶ ̶c̶h̶a̶r̶g̶e̶ ̶a̶n̶ ̶o̶r̶d̶e̶r̶ ̶o̶f̶ ̶m̶a̶g̶n̶i̶t̶u̶d̶e̶ ̶m̶o̶r̶e̶ ̶f̶o̶r̶ ̶t̶h̶i̶s̶ to support further development of this gem.
I'm not really commenting on the price chosen, but the choice to charge for it. I've also created a jQuery plugin or two. I released it for free and now spend a reasonable amount of time answering questions about support, implementation, etc.
For some reason in my mind I had always assumed that open source type things have to be done for free: the building, the support, etc. Seeing someone doing something others helps put that in perspective.
Or, in short: I wish I was smarter about it and more business-savvy.
I'm just one data point but I actually push those "donate"-buttons when I see them on plugins that make my life easier.
Just keep the amount reasonable in relation to the product and don't make me jump through hoops. I.e. just link directly to paypal and if you want to ask me any questions then put that form after the checkout-process where I'm free to ignore it.
