I used Sewell Lexus back in 2004 when I got a replacement shell for my broken ’99 RX300 key. I show them at 214-352-8100, down near Love Field around Lemmon and Mockingbird. A picture of what I got back then is at http://www.sewellpar...l.asp?id=180654
Regarding replacing just the cover of the key, my recollection was that replacing just the cover didn't seem feasible in my case, but I could be wrong. I know that the metal key itself wouldn't transfer to another case -- it was integral to the old case. But your situation may be different than what I encountered.
You might consider calling Sewell and asking about their blanks, and
It appears they sell parts at their store or from the web site at http://www.sewellpar...om/category.asp
. Entering your 2004 RX330, I found several keys for your car at http://www.sewellpar...p...88&pid=1287
. I think you want to end up with a working Lexus Remote Master”, but by using the cheaper “Lexus Key Shell” if possible rather than getting a whole new key. But from their picture, I can’t tell if the “shell” has the holes in it for the buttons – you’ll probably have to ask.
If the “shell” will do the job, they show to charge $57 (http://www.sewellpar...il.asp?id=88781
If you have to buy the whole key, it would be $147 (http://www.sewellpar...il.asp?id=76846
In both cases, just moving the “transponder” guts from the old key to the new will eliminate any “programming” costs.