I've had 3 Subarus now (1986 wagon, 1996 wagon, 2005 wagon) and have hauled dogs in all of them. And bikes.
If you google the Ultimate Subaru Message Board you can find their "for sale" section. Subi lovers selling their beloved Subis. Most are older models and generally the prices are very good and the cars have been well maintained.
At the least you can post a request that one of the USMB folks in your area help you find a used Subi wagon. These guys are always noticing Subis for sale near them.
"If Americans want to live the American Dream, they should go to Denmark." - Richard Wilkinson