Toyota Repair: lost key, toyota avensis, diesel estate

Question
i have lost the only key i have for my toyota avensis 2.0 turbo diesel estate r reg. can you please advise me of the cheapest way around this. to get a new key and get it re-programmed is going to cost a fortune

Answer
On some models the computer has to be replaced if the original master key is lost and on some it is possible to reprogram a new transponder even if there is no master key, the problem I'm having is that I have no idea what an avensis turbo diesel is, they are not sold here in the US.
If there is a toyota dealer check with them, they should be able to look up on their computer what needs to be done.