Hard to help date the bike based on that picture alone.
Batavus is an old established Dutch builder, and known to produce
some very nice bikes.

Normally I'd say check ebay for pricing but you'll find very few Batavus auctions.
There is currently one Batavus Professional on ebay, grossly overpriced.
The course is probably the 2nd or 3rd model from the top (professional).

Components, your location, condition all will play into what the bike is worth,
a better picture (if available) would help us too.

Marty (dutch bike afficionado)