www.car-part.com will give you many junk yard options.
ebay will give you som options.
autozone, advanceautoparts will give you soem rebuilt options.

Call around to local junkyards?  That same engine was used in a number of
Chrysler products, I wouldn't think  you'd have much trouble finding one
somewhere...

My 3.0 Caravan blew its head gasket at about 162k, but didn't mess up the
heads.  $800 or so later, it was back on the road.

Wesley