i was going through same dilemma last week....
If u want to install something good like kenwood or pioneer dvd, it will cost u > 30k....n that too without nav....apart from that, if u go for rockmars or other chinese counterparts, they will cost u around 16-20k with nav....but believe me, there is a huge diff in quality....
i got following items;
Dashboard frame (SGP from Suzuki dealership that comes with DX) = PKR 3000/-
Pioneer AVH-X2650BT = 32,000/-
Camera (0.3 lux) = 2000/-
Female Din from Civic to avoid cutting factory wiring for player = 500/-
Installation charges = Free
Installed the camera over the number plate...its invisible until someone kneel down to have a good look.
it all cost me 37500/- without nav....i was given option for nav also but on pioneer players, it was about 20k additional cost for the device (i dont know what its called but uses an SD card) so i dcided not to go for it....let google maps do the thing on the mobile phone...
the players without BT cost less but i would recommend BT...plus get the mic installed in the designated place in dash (behind wiper controls)
PS: I kept my Alpine just in case i need to sell the car... 