We all love our key less remotes for our cars. Super convenient, great invention. One thing is now there are actually two things that have to be replaced when we "lose our keys." The remote and the key attached to it. They can be very expensive to replace if we own one of those 'newer' cars.
The remote that unlocks the doors you can get on eBay/internet for most cars fairly cheap, even if you have a high end car. You can then program it yourself to unlock the doors. So losing or replacing a bad remote is at worst inconvenient. It's optional, and maybe not even worth doing.
The actual 'key' can be tricky if you have a newer car that has a key with a 'chip' in it. That chip (a form of RFID) is called a transponder and is separate from the key less 'remote'. These chips can look like a gain of rice, or a piece of foil. Normally the transponder chip is embedded in the plastic handle of the key. The transponder is there to prevent theft by removing the lock tumbler and then turning the switch. Possibly they also prevent thief by hot wiring, but serious if a thief is smart enough to hot-wire a newer car I don't think defeating a transponder key would even slow him up.
You can get the key 'blanks' on the internet or local locksmith. You can get the metal key 'blank' cut to match your car's locks. BUT... The locksmith might not be able to set the transponder chip in the replacement key, so that replacement key will not start the car. In that case you end up going to the dealer anyway and paying the gun held to your head price for a new key. Well there is a cheap solution that is worth a try and works with no programming.
You probably have (had) two factory transponder keys given to you when you purchased the car. Instead of ordering one key blank to replace the lost one, order two and have both of them cut. Then tape the remaining 'factory' transponder key under the steering column out of site. It might have to be kept close (inches) away from the switch - you might be able to have it feet away - experiment. The hidden transponder key will respond to the car's security ping and allow the replacement key to start the car. Use the two (or more!) replacement keys from now on to start the car. Lose one of them it's no big deal.
The best thing about this is that you probably won't lose that 2nd factor key since it's attached to the car. Sure this hidden key could make your car easier to steal. You have insurance for thief, and serious how many cars have you had stolen in your life? Now, how many of you have lost a key? If you are really concerned about thief, after awhile of using the replacement keys cut the actual metal working end of the hidden key off or dig the chip out of it. Trying to remove the chip should be tried while you still have both factory keys in case you damage the chip trying to remove it. Then just tape the chip or plastic handle in place. Remember we are taking about the key here. Not the remote.
FYI - There has been no proof from the auto insurance industry that transponder keys have reduced car theft. A teacher once told me that locks are to keep honest people honest. A thief is going to have something to take care of that lock. A car thief (verses a smash and grab the contents) is not going to try and steal your car unless he already knows he can start it (or has a tow truck). So the fact that the thief knows your model of car has a transponder is enough to prevent its thief - until he has the hack to get around the transponder and then it's worthless.
The only thing that has been proved is that transponder keys provide financial security for the dealer. Today it's the $200+ for a new key and remote, maybe another $100 for towing the car to the dealer to 'reprogram' it. But the real security that transponder keys provide goes like this:
"Oh so sorry... The key code for your car is no longer available...Your car is too old...You'll have to buy a new car, and pay us to dispose of that worthless hunk of metal."
Think about it.