Need advice with replacing CV Joint (4.0/4.6)

My driver's side CV Joint is bad and needs to be replaced. My local RR mechanic said that their policy has been to replac the entire axle when a CV joint went bad, however I quickly found that almost every online parts source does in fact sell them seperatly. Any ideas why they would do this (other than the obvious reason of being able to charge more $$$)? Does anyone on here have experience, advice, or directions on replacing a Range Rover CV Joint they could share with me?

Also, I've heard that this is a common part to go bad. Does anyone make a more heavy duty, realiable CV Joint than the OEM part? Thanks in advance for your help.

Just to follow up on my own message, I contacted East Coast Rover (one of the only companies I found online manufacturing upgraded CV Joints, axles, etc.) and here is their reply:

"Unfortunately there are few off road upgrades for the SE and HSE Range Rovers as they are rarely used off road by most owners. The factory CVs will be your best bet for install."

Hope that helps anyone else looking for a replacement CV Joint for a 4.0/4.6 Range Rover.