I'm often asked, 'what are water-mixable oils?, and 'why do I use them?'. I've been using these oils for 10 years. The solvents were causing headaches and the clean-up was labour intensive. My brand of preference is Lukas Berlin Water Soluble Oils. They are very buttery, and 'behave' like regular oils. The 'medium' has been added to the tube of paint. However, I cannot get the 200ml tubes in Canada. The 200ml tubes are only available through Jerry's Artarama in the U.S. (Apparently, they have a North American Monopoly!) When the dollar is favourable and the sales are on, I end up paying about $15.00/200ml tube. (This includes shipping and customs).
Recently, because of cost, I've ventured into the realm of Windsor Newton -Artisan Water Mixable Oil Colour. There has been a learning curve, but out of necessity I've come to accept this option. (Although, Lukas Berlin has a Cinnabar Green that I cannot be without!) Below is an explanation by Lori McNee as to the benefits of these paints that reflect my sentiments.
Why I use water-mixable oils.