£140????? Bloody hell that's a good price! I paid £200 for the rear window alone 6 years ago.
What level of tint are you thinking? I went for light smoke on the front and dark smoke around the rear of the car. I have not yet in 6 years been stopped by the Police. If I had my time on this again I would only go light smoke all round. This level is what I would recommend for your car being black. Any darker would may be too much?
Might be worth a photoshop to get an idea?
;-)