Nice! I haven't bought a toolbox in a while (need to, thanks for reminder) but remember the Sears prices fluctuating up and down a lot. Last one I bought was in 2002 or so, and I watched prices for a while before jumping in around Christmas time. That seemed to be the best price I'd seen in a while.
For liners, I had bought a pack of whatever Sears sells, but later realized they were on the pricy side, and there are many bulk roll materials that would work just as well. For the toolbox I keep in my truck, I cut a piece of scrap floor-runner mat I had got at Lowes. It's black plastic, comes 36" wide, is about 1/16" thick, and has thin fine ribs (which make it easy to cut as the ribs are like guides). You can buy it by the foot. Use rib side up or down, whatever makes sense. I think for some toolbox applications, the thin outdoor carpet felt (about 1/8" thick) might be good too. Could even use thin neoprene roll sheet if available, or really any soft material that has the characteristics you need.
Anyway, I have a mental note to avoid buying "specific" drawer liners unless they are really really inexpensive, since the bulk material works out to a lot less $$.