Land prices in Pittsboro vary drastically. You can find land for $75k an acre or $750/acre. There are however a few places in Chatham County around Pittsboro where land is consistently priced lower than in other areas.
The cheapest land in Chatham is in the Southwestern part of the county. Prices drop significantly when you get West of 421.
To speak in very broad generalizations… Land near Chapel Hill in Chatham is $50k-$100k per acre. Land around the lake is $20k-$50k per acre. Land in and around Pittsboro is $10k-$20k per acre. Land between Pittsboro and 421 is $5k-$10k per acre. Land west of 421 is $2k-$6k per acre.