However, if you run into trouble you are required to pay for support - or hope that someone on the forums can and is willing to help out. This might be a relatively small issue, but there is almost no documentation (the link provided by the developer in these comments returns a 404 error [http://dev.anything-digital.com/JCal-Client/Documentation.html]) and if you're not using it "out of the box" you can spend a *lot* of extra time trying to work it out.
Make sure you read all of the reviews and pay a visit to the forums at AnythingDigital before you commit to this product. When you're billing a client hourly for custom layout, the cost in time can quickly outweigh the benefits of a low initial subscription fee.
I have updated the links for documentation, I appreciate the heads up.
As for support, you get what you pay for, and $20 doesn't go very far given the average fee for programmers is USD $75/hour.