Hello, and welcome to Just Answer. Please allow me to assist you.
In a word, the dealer is right, no one can program a new key withjout one of the original keys. That is, assuming that you have a transponder ignition key...it would have a thick head, where the hole is, about 1/2 inch wide. If you had an all metal key, you do NOT have a transponder key, and any locksmith can help you out.
If you DO have a transponder, you do have options. You could pay the 2 grand for the new ECM and the keys. You could locate a used ECM and keys from a scrapyard, OR, you could go the ECM assistance route, where a company supplies OEM ECMs with matched keys. I do not have the information at this time, my parts manager is off today, and he has the info. You could call the Toyota Customer Experience Center at 1-800-331-4331, they may have this info. If not, ring me up on Monday, and I will get you more info.