Every time I have had a CV boot tear or slip off, the mechanics that I brought the VX to have wanted to replace the whole axle. They said that that was an easier job than trying to replace the boots. That may be, but it's very hard to find OEM replacement axles for the VX. There are a few manufacturers out there that make replacements, but as others have found there are fewer, and smaller, balls in the CV joints causing them to click and clack. It seems like the VX has a unique set up and your mechanic would have to find Isuzu OEM axles, which can get expensive. I have a feeling that he is looking at something like the EMPI replacement axles which are like $70 a piece.
I have had to force my mechanics to just clean the joint out, re-grease it, and replace the CV boots in order to keep everything stock. If you're even slightly mechanically inclined you can replace the CV boots yourself, or bring the below instructions to your mechanic to see if he would do the work.
http://www.vehicross.info/downloads/...ch_Install.pdf
I'm sure others will chime in......
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong, it usually turns out to be impossible to get at or repair."
-Douglas Adams, Mostly Harmless