I decided on bridging ladders instead of sand ladders because bridging ladders can work as sand ladders but sand ladders will quickly bend when used as bridging ladders. The 2 options I found were either fiberglass resin or steel.
If you are looking for the 2" fiberglass resin grating, then ebay has a guy. They are about half price of the terratrax product but are the same exact dimensions and weight. I presume that since the weights and dimensions were the exactly the same, then so were the strengths - possible long leap of faith. I found out about them from a poster on Ih8mud. If you order from this guy, make sure you get the closed ends all around:
2" FIBERGLASS MOLDED GRATING, VINYLESTER RESIN - (eBay item 120200251791 end time Dec-28-07 19:51:54 PST)
I went the cheapest route I could find which turned out to be $60. I purchased some WWII surplus Marsden Mats which are the extremely similar to the steel mats sold here:
OKoffroad.com 4x4 Recovery - Sand Ladders
They were basically used as pre-formed "instant" airplane runways. I figured that if huge military planes can safely land on them, then our 2 1/2 ton vehicles cant hurt them. Read about them here:
Marsden Matting - Wikipedia, the free encyclopedia
They are also called PSP or perforated steel plate and I found out about them from a post on a jeep forum.
They come in either 5' or 10' lengths. I purchased one 10' and had it cut down to two 52" lengths (5' would not fit in the back with seats down)and then had the side hooks cut off to try and save some of the interior plastics (no roof rack on mine). They have most of their surplus painted finish with a light surface rust in areas and weigh close to 30# each but they were cheap (so am I). I haven't had a use for them for anything as of yet but they're nice to have as insurance. I purchased them and had them plasma cut down from these guys in Mojave, California: