When we bought our house this summer, there was a gas stove retrofit that also fed the pool heater and an outdoor grill that had a leak. We made the seller fix all of it, so they had a plumber dig and run a new gas line for all 3 appliances, I think it cost in the neighborhood of $2000.
All the appliances are on the same side of the house as the meter, with an existing tee for at the original line for the furnace that goes off to the attic. They ran about a 10 foot new line under ground to the stove and the pool heater, came up and attached to those applicances, then tee'd off of that and ran a line another 15 feet or so to the grill. Plumber had to hand dig it all.
So back off that for just a stove hook up and maybe you are looking at $1000 as a ballpark worst case for just a stove depending on the location of the meter and existing lines.