Great news! You can now download WPF samples individually.
From the WPF samples page on MSDN, just go to the sample topic of your choice, click the “Download sample” link on the page, and follow the instructions! It’s fast and easy!
Note that if you choose the “Unzip” option, you will have to dismiss two of the same dialog box before the “installation complete” message box shows up. That’s a known issue that's currently under investigation.
Special thanks to John Knox, our wonderful build developer, for helping us make this work!