Nice how to on building your own window box planters from DIY network. Brighten up boring window with the neat looking planters. I love the look of flower boxes under windows.
The site has a step by step tutorial and give a cost estimate of 50 to 100 dollars depending on the size of the box you need. Very nice diy project.
http://www.diynetwork.com/how-to/how-to-build-a-window-box-planter/index.html