Keep your eyes open, and check on some of the fleet sales. The Transit Van is getting a few years under it's belt and I imagine that some should start showing up on the Used market.
If you know any companies in your area that uses the Transit Van, check to see if you can get on their mailing list when the sell off unneeded equipment. Especially with the economy in shambles, there will be some companies who will need to sell off excess equipment.
Siemens, ADT, CPI, SafetyKleen, UPS, dozens of HVAC/florists/computer/courier services are using then around here. Should be some available in a reasonable time frame. Have 62K on mine and never done anything except oil changes. Put on a new set of Michelins last week.