There are several brands of Solid Surface materials. Corian, Wilsonart and Formica which are the leading suppliers in the U.S. All are comparable to one another in quality, the difference is the variety of colors. In most cases, before you can purchase the material from a distributor, you need to get certified by the distributor. This usually involves on sight training, approximately 4 hours at the distributor, in some cases they will do it at your facility. Regardless of what you are doing with the materials, most of the time they require the certification for material warranty purposes.
We too have been making signs, inlayed coutertops and more with this material for years now. It is great to work and not that difficult to do. As stated by Inlaying Corian, it is more expensive upfront but worth it. The material comes in sheet sizes that are 30" or 36" in width by 144" in length, be carefull in handling.
To find a distributor for any one of these, try the following links.
www.corian.com
www.formica.com
www.wilsonart.com
Good luck.