Can't remember,well less than a tenner for the litre. It is biodegradable and I'm converting to acrylics to get away from the chemical plant in the model room! I've even found an odourless solvent for artists oils (which I still use for washes and filters).
My beloved WEM colourcoats, which are superb paints, now see less and less use.
I'm trying to use less white spirit, turpenoid, methylated spirit, lacquer thinners, lighter fluid,ammonia, acetone etc, I'm sure you guys know how long the list can be!
I now thin acrylics with water (along with a drying retardant and flow aid) and only occasionally use a harsher solvent to "deep clean" an
airbrush.I'm not a green nut, I'm doing it for me and am not trying to tell anyone else what they should or shouldn't use. The hobby can be challenging enough without someone preaching at us! I did, once upon a time, qualify as a chemist so I do know how unpleasant some of these chemicals may be, particularly with frequent exposures.
I spent this morning at the spraybooth and even after cleaning up there was no discernable odour - lovely!
Cheers (fragrantly)
Steve