I'd replace the lot also... better safe than the alternative. Unless you want a stolen bike Bro.
Getting a key made, unless you can verify your the owner Honda will not make a duplicate key. Usually a key Number is required and that information is only on the key, or key tag. Without it, according to the owners manual the ignition / PGM fi system may need to be replaced. The owners warranty and service policy manual says the only record for the key is on the tag, or key-
I don't like your chances in getting a spare...
I'd contact a dealer first, and check out all your options. I wouldn't buy a second hand ignition either.
WHO has got a key to it when you buy a second hand one? - it may work it may not. Is it worth it?
Spare keys - their keys have magnetic circuits specially coded that if not recognised will not work.
Its part of Hondas HISS security system to stop people- albeit in vain stealing your bike as EASILY.