Hi Speedy
this is an especially tough one because it is from a very poorly documented period in Universal Geneva chronograph history, roughly 1960-1972. These late Aero-Compaxes in particular exist in so many references that I have no idea about production sequence, rarity, etc. I'd suggest letting the market decide - stick it on ebay, straight auction, PayPal, international shipping (no PayPal, domestic only restricts the market and the price). Just to take a (conservative) stab at it I'd predict a price north of USD2500.