Tell her you will pay for the new CV or Axleshaft, but anything else that breaks when it lets go is coming outta her fun money. Let's see; wheel bearings $500, differential $1500 (used), Misc. suspension components beat to death by loose axle shaft $$$$.
Seriously, it's not THAT bad of a job to replace the thing. I replaced the left one on my '87 560SEL about a year ago. BTW, how are your flex couplings? Mine went about the same time as the CV.