Many locksmiths can duplicate RFID/chip automotive keys these days.
They have an electronic device that can clone the RFID chip in a working key.
Then they cut the key. Done and the key works.
It's much cheaper than the dealer and perhaps the "best" way for the TSX since there is no way you can program your own RFID keys with the TSX unlike many other cars.
With most other cars, even perhaps on newer Acura's, you can program a 3rd or more RFID keys yourself as long as you have 2 working & different RFID keys already.
This is why buying a 3rd RFID key is so highly recommended on many car models.
The Lombard Locksmith I went to had the machine to program my key to the immobilizer. They even programmed the keyless buttons too which I didn't mind. Great deal for $35 and definitely cheaper than if I went to the dealer.