I had tried all over town to get extra keys for my bike ('73 CB500/4) and NO one had a clue, even the ace hardware and several lock smiths.
I was getting pretty frantic having only the one, pretty worn and bent key. One day, for the heck of it, I searched eBay (
31J honda key* in titles AND description, for instance with your key as example) and voila! some guy was selling a bunch of factory Honda keys and had mine!!! I picked up 3 of them for $12 total, I think - I doubt you can get generics cut for much cheaper!
I just did that search for you and nothing is coming up, however, the guy might have sold them all or something.. . .if your other source doesn't pan out, keep trying the eBay and they might turn up. I am still amazed at some of the stuff for these bikes that comes up, from time to time, there. . .