Yeah - it will be next to impossible to find one for under $50k. If you want Diesel - count on mid to upper $50k region. The Audi allroad is in the same boat. The main problem with these 2 besides the price is the difficultly in fitting 2 adults and 2 kids older than 12 (or 4 adults) for a 3-4 hour drive. I happen to prefer wagons, but at this price you might as well get a Jeep GC type SUV for less money. Some of these trucks are now available in diesel form.
Or even a new Outback...Granted the mileage isn't near the same but how long will it take you to make up $20K in OTD pricing? You might not have the refinement but you still have a very good AWD system.