To change the color of ur vehicle in the excise documents is almost impossible bcoz a lot of verification then required which will bring you to a point that you will like to burn ur vehicle so why opt for a doubtful vehicle which only bring problems.
BTW the prizes of all 4x4 are up now, like well maintained Surf of 1996 is now around 17 lacs. older version of surf which are without 1kz are still range b/w 10 to 14 lacs depending on the model and condition. I owned a 1997 recondition 2007 surf from the last 4 years which I kept well maintained and done 180000 km till date. I am not selling it but I still have 5 offers from my friends and the last one was 19 lacs and the reason is that one cannot finds a good clean vehicle in the market. Market is full of custom amnesty vehicles but as mentioned above in a comment, they are roughly used and slow in resale.