Footprints are nice to keep your tent clean when the ground is wet/muddy. But the offerings from the tent companies are overweight/overpriced IMO. Take the advice above and just cut your own. They're very simple. It's not like you're trying to make your own canister stove.

Better yet, recycle something else to make your footprint. I once used an old plastic tablecloth that was tossed in the trash after a work party. I got quite a few miles out of it.