Having been in production for over 20 years, the Jaguar XJS today can vary in price from $400 - $700 for an older coupe, to over $38,000 for a late V-12 Convertible.
In the United States, the coupes can be had in rough shape on a regular basis for $800 - $1,000 and convertibles bring anywhere from $4,000 - $15,000 depending on year and condition.
In the UK the best of the market is often considered by enthusiasts to be the mid-80's coupes. The rare 6.0 liter cars usually command a premium price in the US market with a 6.0 liter convertible bringing top dollar.