Used iMac 20' 2009 model

I am considering buying a used 2009 iMac 20" intel core2duo.

It is from a personal owner. Includes the following:
Fresh install of OSX 10.6 Snow Leopard.
Comes with Microsoft Office for Mac 2010, iLife 09, iWork 09, mouse, keyboard and OS disks.

The specs are as follows:
20" LCD display
Intel Core2Duo 2.0 ghz
2GB RAM
250GB HDD
Generation Build: iMac 7.1
L2 Cache 4mb Bus 800mhz
This machine is no longer eligible for Apple Care.
I am new to Apple (currently pc user "windows xp")
I am returning to college and need an update all together. Family members have an Apple computer.
My question is should I be concerned if this is out of Apple Care eligibility?
They are asking $650 for this used unit. No blemishes, no dead pixels, no downloads other than what is mentioned. No games played, etc.

What should my concern and questions be on a used purchase? Is the price high for this model year?

Any advice or feedback would be greatly appreciated. Thank you.

Check it out on this site Mac2Sell and comparable units selling on eBay and Craig's list. Also, there is no such application as Mac Office 2010. It may be Mac Office 2008 or the new 2011. Office 2010 is a Windows version.

The price is fine, and when you say OS discs, do you mean the original install discs? If so that is great. And remember if a seller is 'asking' x amount, you may be able to get it a tad cheaper.

Ask to see it running and run Verify Disk in Disk Utility and run DVD/CD discs through the machine.