Lost only ignition key?

There is no cheap way to do that. Honda is very proud of their keys and security. It becomes a toss-up really. The dealership would most likely be more expensive but not all the time. The next would be an automotive locksmith. They would come to your place, look at the VIN and then verify you own the vehicle. Then they would either look up the key codes through Honda or just use a decoder to read the code from your cylinder. Then they would cut 2 keys and use a programmer to erase the old key(s) and activate the new ones. Be very careful of the ones you see online claiming a new key for $50.00 those are blank uncut keys and many of the ones I've tried after a customer bought them worked physically but would not actually program into the system.