Buying a specific used car

Hi,

My husband and i will soon be buying a car through a dealership for the first time.  I'm
pretty specific on what I want--a certain year range and trim of minivan in a certain color.  
This ideal car isn't in the inventories of any of our local dealers, but there are plenty in the
cities around Chicago (a couple hundred miles from us), and we could easily get
ourselves there for a couple days.  I know you aren't supposed to go to the dealership
under any sort of time crunch, which we would definitely be under.  Should we call ahead
to a few and try to negotiate before we make the drive?  Once they find out we are from
out of town, will it give them the upper hand?

Alternately, is it possible to work with a local dealer to find a particular car?  I'm sure they
have resources for buying/finding/shipping that we just don't.  However, this would give
them all the power when negotiating a price.  Any thoughts?

Thanks