Crazy money at the moment I started looking for one about 10 years ago and I thought the prices were way too high back then. They've doubled in price since. Like you, I had a Mexico avo and sold it for next to nothing back in the 80's.
Funnily enough I found an old car magazine a few months ago, dated 1983 and had a quick flick through. Loads of RS's, Mexicos going from £500 to £2000.
If only I had a time machine