There are plenty of stands out there that are not made out of 2x material.
Billdogg explained very well why many people choose to go the overbuilt route.
It is a matter of one's personal confidence in building one's own stand and the availability of materials and tools.
I built a cabinet-style stand for my 120 gal system with solid rift-sawn red oak.
It was built without any 2x material and has been in use for about 18 months with absolutely no issues.
I actually just completed a second build of the same design (photo) for another RC member this week.
<a href="http://s32.photobucket.com/user/jason_langer/media/ReefCentral/Salinero-finalstand-2-email.jpg.html" target="_blank"><img src="http://i32.photobucket.com/albums/d4/jason_langer/ReefCentral/Salinero-finalstand-2-email.jpg" border="0" alt=" photo Salinero-finalstand-2-email.jpg"/></a>
If you would like to get more information about cabinet-style stands, read through
billdogg's thread or my own
build thread or any number of others.
The build thread's include a lot of photos and instructions to help you along the way.
Good luck with your build.