ways to find invoice prices for cars?

i'm in the market for a new car and i've been looking at truecar.com and edmonds.com. when i put in the info, they seem to be right. are these sites a reliable way to figure out the invoice prices? any other sites you guys know of?

 

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If you drill down into spefic cars go to the prices tab and you can get a summary of what others are paying as well. I use this all the time.
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truecar.com is very good. some interesting stuff there.

 

edmunds.com another good source.

 

I usually use the consumer reports website.