WMV (not wma, that audio) doesn't offer that well compression. It is used mostly for streaming video.
Divx and Xvid offer much lower files sizes and much better quality of WMV.
I WOULD NOT!!!! recommend buying a program for $30. It is just a waste of money. There are other ways that offer much better quality, that use all free programs. Here is a great beginers guide.
http://www.aximsite.com/articles/link.php?id=215
It is free and it works well. There are even some better programs (free) butter require more knowledge. For example virtualdub.