Yes, it's a good bike. Elvish made very good bikes in the south of France for a very long time. The bikes disappeared here as the Japanese got good at bike building during the early '80s and started to dominate the market.

This one appears to be in pretty good shape, with minimal rust and good/appropriate patina. Tubing is Reynolds 531, which has very good ride properties. You'll want to go over the frame very closely to ensure that there's no bending. front-end impacts, dents, etc.

Pricing will be key. The bike won't be a rip-off if priced under $500. Elvish wasn't spectacularly well-known or particularly collectible.

The bike is French, so normal French bike caveats apply - e.g. exact replacement parts are old/French/in dwindling supply. You will want to check the Simplex derailleurs to ensure they have no cracks in the Delrin. It'd also be best to check the Pivo stem for cracks, even though those stems weren't infamous for being "death stem" types (see - http://theheadbadge.blogspot.com/2012/08/death-stems-demystified-ava-and-atax.html).