Advert alert!! Lol....
Well I ordered a spare key for my IS last week and I went to Lexus Bristol today to pick it up. They coded it for me, £35 for the coding and £133 for the key!!
I asked the guy sat in my car coding my key if he could clone a key from a valet key if it was programmed to the car as we still don't have a spare for my wife's IS. His answer was categorically NO! You need a master key.
I'm sure this fella above "the Keyman" can get around it as others I'm sure have done to but Lexus won't do you a spare key unless you have the master.
I also asked about 2 and 3 buttons. Lexus guy said 90% of IS's came with 3 buttoned masters but some did come with 2 button masters, normally earlier models on V, W and X reg :)