A portrait from a photograph in technique of watercolour are on thick paper. Such portraits look easy and scenic!
The cost and production time are dependent on image (a portrait from the chest to the waist with the same format are different) and format.
Single RUB "without hands, chest-high":
A5 — 4000 RUB A4 — 5500 RUB A3 — 6500 rubles.
It is possible to make a decorated picture "turnkey", but the price will add the cost of a baguette of glass and a pasteboard.