That is actually residue from Power Steering Fluid. Started to sweat a bit of fluid 6 months ago, it would never leave more than 1 drop on the pavement. I put in fluid for cars over 75K to recondition the seals.
It should be ATF, that's probably why it leaked out in the first place. Does the power steering whine or have any other problems besides the leak? you might want to start the turkey baster routine with ATF.
This rig was listed here on MUD maybe 9 or 10 months ago (something like that).. Why are you selling? Was there something that you found out? Any smells? Coolant leaks?