Tips on Negotiating Car Prices?

Whilst i feel the above post is an attempt at viral marketing here is some information that may be pertinant.

In Australia data on used car prices is available from "red book" online.
Input the make model and year and the Red book website will advise on a the price range you should be dealing with. The condition of the car and features will affect the price.
Here is an example from The Australian red book for a 1991 300 series Mercedes benze.
http://www.redbook.com.au/used-cars/details.aspx?R=85098&__Qpb=true&Cr=0&__Ns=p_Make_String|0||p_ClassificationType_String|0||p_Family_String|0||p_Year_String|1||p_SequenceNum_Int32|0&__N=2994%204294951785%204294843100%204294965382&silo=1300&seot=1&__Nne=15&trecs=1&__sid=12FB13F4876D

Btw the light reflections on the front right guards on the car in the photo indicate signs of damage. check it out thouroughly.
Maybe its just a trick of the light.