Unless you're determined to have the actual keys with the little button on the side, you might want to look into getting an after-market multi-function remote. This same problem happened to me; they keychain loop to my key with door remote broke off completely, and i went to three different dealers (both toyota and lexus) to see how much it would cost. They wanted between $450 and $650 to replace the key, the remote sensor in the vehicle, AND cut a spare.
For the same price, I found a Clifford door lock/alarm/remote start on Amazon, and had it installed. This remote has approximately a half-dozen different functions it can perform, including popping the trunk, popping the gas cap, pretty much anything you want that is electrically wired in the car. I was able to get the system AND the installation for just over $400...
To Hades with the OEM key remotes, I say.