Hi mate,
Dont mean to sound rude but are you planning to paint you door yourself...if so are you experienced in painting?
The reason I say this is silver is an absolute pig to paint, if you want a really nice match to the rest of the car.
I have resprayed loads of cars and wouldnt consider doing silver anywhere other than in my mates oven with its excellent lighting,
and even then, with a door, I would probably fade it out half way through the wing and rear quarter and then clear the whole side...if not paint the whole side of the car.
The problem is with silver is that the colour varies massively depending how it is applied...
lay the base on heavy and it will be very dark...
lay it too light and it will look very course (almost like a metalflake)...
if not applied evenly it will be stripey...
even variation in air pressure will give annomolies in colour pigment...
Drop coating can help ( a very light coat dusted over after, from a kind of step back away from the car, to give an even finish if doing a complete repaint...but on a panel it will just make it look grainy)
Preparation is critical with silvers too, any excessive scratching or scoring from keying up will show up like a sore thumb through the finished paint.
With silvers it will not cover anything thats not perfect...it will "amplify" it when finished and cleared.
I am up for anyone having a go at stuff themselves and will always give whatever advice I can to help,
but if your car (other than the door) is really nice looking it might be plan to find a local bodyshop who will match the paint to the actual colour on your car from their scheme, and paint it for you.
Cost would obviously be more than doing it yourself, but I genuinely fear if you buy the materials and do it yourself, then you will end up at the bodyshop anyway, unhappy with the results (and probably end up paying more as panel need more prep to undo the work you have done).
I really dont mean to sound insulting by this post, but I have had nightmares with silvers before that have cost me money instead of earning it...
and I have painted cars for years and do custom work so should be able to get it right probably more than most...
If you car is a scratched up offroader go for it yourself...if it is a pretty, tidy example, please get a bodyshop to do it,unless you are really confident.
Useful tip...if you know anyone locally who has a car front or fleet of vans, ask them who does their trade paint work, and how much they charge per panel (normally how its done) you will be suprised how little it can cost if they are putting a fair amount of work the bodyshops way.
We used to charge £75/panel to fit and paint inclusive of paint but with cust supplying panel for trade jobs...and thats about the going rate round here.
Bearing in mind the bodyshop wont have to fit, and wont have a whole car clogging up their workshops/booth...I reckon you should be able to get it done a fair bit cheaper especially for cash.
That way it should look right and wont cost a whole lot more...by the time you have bought primer,basecoat,thinner,lacquer/clearcoat,scotchbrites,masking materials etc
Hope this helps you mate...again no offense intended...
Laters
Gregster