The driver`s side door handle cable broke. Found out that Jaguar no longer carries the replacement part. My local shop said they found a used part and that the repair is $330.00 Is that reasonable?

 

That's probably not too far out of line. I have the cable available if you want to try it yourself.

 

FreedomFirst, The most helpful part of a post is to know what type of vehicle we are dealing with. It is best to put that info in your signature. Assuming you have an x308 the cable for 1998 to 2001 is around $60.00 bucks and for the 2002 to 2008 is around $79.00 bucks. These are new cables available from JAGBITS.
When i changed mine on the 1998 XJ8 i bought it from them. You can find there site and take a look at what they offer. They have an option of emailing them for parts inquiries. They answer promptly and ship quickly. Let them know you are with the Jaguar Forum and they offer a 10% discount.
With a quick search I saw they had complete door actuator assemblies with cables for only $150.00.