I can't help with figures, but from my guess a colour change is going to be expensive and labour intensive. You'll be looking at colour changing the bits you don't see i.e under the bonnet, insides of the door shuts and any other bits i may not have mentioned. I know if I were in your shoes, I'd go with the original colour, it will probably make you fall in love with your car again once you see it looking freshly painted. The other side of a colour change will be that it usually devalues the resale value of the car.
Just a bit of food for thought, but a fast and cheaper way of colour changing your car would be to get your car wrapped, its probably half the expense of a full on respray and looks pretty amazing when finished.