My guess is that the area along I-78 in western Berks or northern Lebanon counties would have the cheapest land within two hours of Philly, or the best chance of touching 10 acres for $250k. The northwest side of the Great Appalachian Valley is shale not limestone so the Plain Sect farmers don't want it as much, and commuting to jobs in Harrisburg, Allentown, or Reading gets pretty far from towns such as Fredericksburg and Bethel.
If you can push out your 2 hr window a little bit or depending on what you mean by Philly "area," the valleys of Northern or "Upper" Dauphin County, and adjacent parts of far west Schuylkill and southern Northumberland, counties might open up for you. Towns to get you started on a realtor search would be Elizabethville, Klingerstown, Herndon, and adjacent. Add: Auctions seem to be the main way places like you're talking about, convey in this area.
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