Buying Advice - Looking at Cars

Does anyone have access to the auction pricing for 2008 and 2009 E60's with under 50k miles?

CPO I am seeing anywhere between $50k-$60 for 2009's and $45k-$50k for 2008's.

Non-CPO are not that much less. I am aware of good 3rd party warranties with a company like NAC, but what is an acceptable price for an M5 like this:

http://www.perillobmw.com/certified-...99C043025.aspx

Any advice on how to approach negotiations with dealers of CPO and Non-CPO cars based on the auction/trade in market? Any advice would be great. I am really close, I am going to test drive a local '07 with SMG that's for sale at a local Porsche dealer to see how I like the SMG. I am coming from a manual S4, so I don't expect any real issues.

I have driven a few beasts:

The first is an 08 with 37k miles priced at $44,900

The second is an 08 with 54k miles priced at $40,500

The third is an 07 with 60k miles priced at $39,900

Based on my driving experience I loved all three cars. I can get at least 2yr/24k mile warranties on all of them and even a 3yr/36k warranty (that covers the full SMG including the clutch).

The 08 w/ 54k and the 07 were taken in on trades with the 08 having only 1 owner.

What should I be paying for these three cars? I used Edmunds and it says a fair trade value would have been in the $34k +- a couple of grand for both 08's and $30k for the 07.

I'm leaning towards the 08 54K because it was 1 owner and serviced at a dealer I bought my X5 from. Opinions?

If you can afford an 08 or higher I would absolutely not even consider an 07. The facelift took place in 08 and there were some significant improvements on both the inside and out.