the dvd player is prob worth more than the car...
but if you insist on having it put in then get in touch with these http://www.cablexcaraudio.co.uk/
they are VERY VERY HIGHLY RECOMMENDED by me and family & friends who have had cd & dvd players installed
just a word of warning, be careful with it installed and keep an eye on your car overnight
i had a DVD player installed on an old car of mine (52 plate KA) and it was all wired in by cablex properly to the handbrake and there was a digital aerial all wired in properly and it had bluetooth and stuff so all that again was connected there must have been about 2 miles of wiring connecting it all in professionally and that night, yes less than 12 hours later, some complete... person... (to go all Ian Holloway on you) decided to RIP MY DOOR OFF my car with the alarms blurring out and then rip the dvd player out literally snapping ALL the wires meaning whoever took it found it absolutely useles because it was all wired in and programmed to my car only and even if i got it back, it would have cost too much to re-fit it because all the cables and wires were ruined...
on a modern car with decent security, yeh i'd go for one (half considering getting one for my new astra) but on an older car with doors made of tin and shocking security features (anything pre 2004 really) i seriously wouldn't bother
but if you must, go to cablex
very very good guys and fantastic prices