Coroplast is certainly recyclable. It is polypropylene; the same material cottage cheese containers are made of.
The bigger problem is finding a commercial recycler. Most local communities will not take commercial waste. Community household recycling is subsidized by tax money. The last few years the costs have risen dramatically because China and other countries no longer want or need our recyclable materials. Cardboard, at present in our market, is negative 4¢ per pound. I found our local recycling agency was paying $80.00/ton for some guy with a flatbed to "take it away" (likely to some un-authorized landfill).
Commercial recyclers will buy polypropylene, but they are much more interested in commercial waste from factories that make polypropylene products, which can run into tons daily. If you can find one that will come out and pick up your coroplast scraps, you will likely have to pay for the convenience, and the only money you will save is the landfill tipping fee (usually around $30/ton).
If you are generating a few pounds per day, It is a much more economically and environmentally sound practice to just throw your scrap plastic in the dumpster.