I called around to a few places and this is what I learned.
Regional Supply has white ABS plastic in 4' x 8' sheets. They sell it by the sheet for $27.16 and there is no scrap to be had so dumpster diving isn't an option. They also don't have anything in the .080" or .090". That is the thickness that Doug (jedi5150) said is what most of the legion has for their TK kits. Regional Supply has .060 and .125 but nothing in between. Special ordering isn't an option because we'd have to order it by the pallet. 50 sheets to a pallet would run about $2400. We really need a rich benefactor in the garrison.
They do have it in a .093 (ish) in black in case anyone is interested......*izzi* cough, cough.
Laird Plastics said they would be willing to price out some scrap for cheap but the thinnest gauge they have is .118. I suppose the next step is to take a trip there with some plastic to see if they can attempt to match it as best they can. I won't be able to get to that until sometime next week at the earliest.
I don't know how plastic strips of different thicknesses look when they're put together so I'm not sure about either route.
Aaron, thanks for the Trooperbay link. The only issue I have with that is there is no thickness listed for those strips so I'm not sure if $12 is worth it or not. I've emailed them to find out the thickness. Personally it seems a little pricey for 2 strips of 4 x 16 inches but it's good to have the option anyway in case others might need it.
I'm still looking around but any other information and / or suggestions is most welcome.