The sites mentioned were:
http://www.radiantvista.com/
http://www.betterphoto.com/
According to our software vendors, there is no upgrade path for Elements because it is so inexpensive. The latest Mac version is 4.0. The latest Windows version is 5.0
No matter what version of Elements you have, Elements 2.0 included, you just buy the latest version. You don't have to worry about missing versions.
You can purchase locally or online. Many vendors such as Amazon have specials and offer rebates.