Does anybody know where you can buy Renault parts at reasonable prices?

Hi. I'm a frustrated Laguna II 1.9dCi tourer owner, and I'm loathed to pay the ridiculous dealer prices from renault! I have been unable to find anywhere where I can buy the parts I need for my car on-line. The problems I need to sort out on my car are as follows;
Need to fit a new clutch master cylinder.
Need a new reverse sensor switch.
Need a new tailgate lock.
Need a new rear wiper motor and spindle.

If i could get the parts cheap enough it would make my car worth wile keeping, as I do like the car!