If you can find it, Guerlain Vetiver soap is wonderful (they don't make it anymore). It also comes in this very nice plastic shell/box that keeps it dry in the shower - very classy. Here's what mine looked like:
The Guerlain 'vintage' Shower Gel is also very nice. I have not smelled the 'new' Shower Gel, which is very easy to find (seen it on Amazon, etc.)
You might want to also try the one from L'Occitane (Shower Gel, not soap) but IMO it's not very vetiver-prominent.
Also when we had the Basenotes New Orleans meetup in 2011, there was a store in N.O. called Bourbon French and they make a wonderful vetiver soap. Not sure if they have a online store, but I guess you could Google them.
I think the smell of vetiver in a hot shower is a wonderful smell! I'd love to smell the Malle, but like you I'm scared at the price. $75!!