Dear Growl Developers
First, thanks for continuing development on this application!!! I think its great!!!
Regaring a charge for this app. Im OK with buying an app. Its a little over a dollar for an app I use everyday, which I think is reasonable. However, i think that you should have very clear instructions to users who are upgrading that there will be a charge via the App Store (I followed the upgrade links in 1.2 and there was nothing that warned me of the price unitl I was on the App Store).
Also, you should explain why there is now a charge. Growl has been a no cost option for so long, that users have become accustom to its price. The fact that youve changed the price without telling anyone is a problem (not that youve decided to start charging).
I think if you put a short explination that you want to continue bringing users this fantastic app, but due to rising development costs (equipment costs, or whatever your costs are), you need to start charging a nominal fee. Users would be more open to this type of explanation that just a SURPRISE! You have to pay now that youve uninstalled the old version!!
Best of luck, and keep up the fantastic development!
MotoDC about
Growl, v1.3.1