Kelly Blue Book www.kbb.com
will tell you three prices.
Trade in (Lowest price)
Private party (Middle price)
Retail (what a dealer would sell it for - Highest price)
Also you enter your zip code so it already takes into account supply and demand in your area when calculating a price.
I bought a 2004 HCH CVT in California for $2000 under MSRP, or $19,300.
I sold it recently, with 22,000 miles on it, to a private party for exactly what KBB said it was worth in my Southern Califoria zip code, $21,000.
So I made $1,700 profit and got a free car for two years, that averaged 60.1 MPG.
Then I bought my 2006 HCH2 for $1000 below list and get $2,100 back with the tax deduction.
So this new car was better than free.
I love this.
BTW dealers are not charities.
They are businesses.
Of course they resell your trade in for more than they gave you for it.
Nothing wrong with that.