Converting from Oil to Gas - Run line through neighbor's yard?

[David Santore]

I am in a duplex owner/occupy with two oil furnaces.  I'd like to convert to natural gas, but I am in a long driveway at 340 feet.  The gas company will give me 100 ft for free, and then it is $30/ft for the rest of the 240 feet - $7,200 to run a line...ouch!

Across from my neighbor, it's a shorter distance.  Unsure how long, but certainly not 340 feet.  How common is it for people to run lines through an easement of someone's property?  Of course I'd need them to be OK with it to start.