Last year I started my WordPress.com blog using a free template, and I paid $30 for the ability to edit its CSS properties. I simply changed some fonts and widened the blog's content containers.
The other day I got an email from WordPress stating, "Custom Design costs US$30, and it is set to on January 30, 2013. If that upgrade expires, any customizations you made to your theme's CSS, Custom Colors, and Custom Fonts will no longer be active on your site. Your site will revert to its appearance before you started using Custom Design."
When I purchased the Custom Design in 2012, I knew the $30 was only good for one year, but I had no idea that my alterations would disappear if I didn't pay another $30 in 2013.
This "subscription" facet of the Custom Design is not mentioned on the Custom Design store page, but it is mentioned on the CD support page...all the way at the bottom.
For someone like me who only needs to make a few adjustments to a blog's appearance, I don't think $30 annually is worth the cost. On the other hand, WordPress.com does host my blog for free so I will pay the $30 annually. However, I only wish that this policy had been more obvious when I initially signed up for the Custom Design package.