The Delta paint shop in ATL takes anywhere from five to seven days to paint an aircraft. That includes removal of any flight control surfaces that need to be painted off the aircraft and rebalanced. Next would come masking of windows. Then either stripping or sanding the existing paint. A final wash before masking and prime coat. Followed by masking and top coats. The last steps are re installing the control surfaces and applying required placards.
To paint something like an A330 you would be looking at a figure around £150,000. That is in Europe. It is probably cheaper in the Far East due to the lower man-hour rates and the fact that health and safety is not one of their priorities