If you have a good socket, and the nuts aren't too damaged, you can re-use them, if you use the appropriate Loctite (about 242, the red one).
I mean, you are supposed to replace them, and I usually do on a customer's bike, but I have run the odd 'dog-eared' one on my own.
They are made of pretty soft material.
I don't know about getting them from a hardware store here, but you may be able to find generic ones from a fastener specialist or a bearing supplier who deals in SKF bearings.
A forum community dedicated to Ducati owners and enthusiasts. Come join the discussion about reviews, performance, modifications, superbike racing, riding gear, classifieds, troubleshooting, maintenance, and more!