Couple of years ago I lost one of my two original keys for my 2012.
Long story short.... It cost a great deal of money and time to have the dealer replace and program a replacement key. Probably close to $400. I did go to local locksmiths who claimed they could do it for less first, but they were unable to. The locksmith option MAY have changed by now, but still would be over $200.
But after having a replacement key made I found the missing key.
Catch was it was no longer programmed for my car as in the process of selling/programming the newest key the key transponder codes were reset.
So I had a useless third key.
Here's the key point of this post:
An honest and helpful locksmith informed me that if (that the big if) one currently has TWO good transponder keys that on some cars (including our MiEVs it turned out) it's easy to program a third key yourself.
I did it, and it worked first try. Took about one minute. See details of method, below.
Point being, it's cheap and easy to get a third key if you don't wait until you misplace one of your two originals.
Keys with the required transponder for our MiEV's now appear to be available from third party sources far cheaper than the dealer.
https://www.ebay.com/b/Key-Blanks-for-M ... n_21484646
Some very cheap, apparently, at under $20..... particularly if you're happy to have a transponder key that will open and start the car and do everything.... except it does not have the remote door opener buttons. (BTW... These are sometimes called valet keys... and I believe they, unlike the full function door-opener keys, are waterproof and could be hidden outside on the car or taken swimming.)
Essentially, the programming procedure for this third key goes like this:
"Insert one of your two working keys and turn the ignition to the 'on' position for at least three seconds (the car does not need to be started), then repeat the process with the second key.
Now insert the new third key and again turn it to the "on" position for another few seconds. This should program the extra key."
Of course you'd have to first take the new key to a locksmith or hardware store to get the blank shank cut first.... otherwise you'd be unable to turn it to the on position at that step of the programming procedure.