Latitude D 6xx series ....cannot tell by the picture if it's a D610 or D620 or D630. I have a spare D630..unusable now.
They were great laptops at first.....solid performance. But many of them shipped with the nVidia graphics that has that GPU overheat issue...and it is a showstopper if the unit is out of warranty...which I'm sure they are. Mine has the issue...I did the "oven trick" on it and it worked for another 6 months or so..but now it's dead. If you have an affected model (you won't know unless you have the service tags)...you basically have a paperweight, I would not purchase these in hopes of reselling them. They're probably cheap for a reason.
as per the nVidia issue - it would only effect the D630 and the D620s should be fine. If the D630 has the nVidia card, make sure you sell it AS IS with NO warranty.
If any are D630s - you might as well throw them away. If they are D620s, they are worth about $125 a piece in working order.
The D420/30 machines are worth about the same.
For a lot of 10 of any of these machines (minus the D630), I would pay around $400 (including shipping). You will spend another $350 on parts such as new touchpads, batteries, bezels, etc... leaving you with about $250-300 profit. I know the math does not add up when you calculate that... but expect 1 or 2 in the lot of 10 to be parts machines that will be too banged up to sell.