I've seen some for sale on the local Craigslist over the last few years. I think I have an extra set of 2017 mats but I don't know if they would fit a 2011.
I'd recommend finding out which years will interchange with 2011 and then looking on your local CL or FaceBook marketplace. Or find someone parting out a crashed Leaf. There seems to be more and more of those around lately too. Or worst case, ask a dealer.