My IL's just did it this week. I called her and this is what she said:
National grid didn't charge them because they were within 100 feet of the gasline.
their grand total was 9500.00 that included:
1,000 for permit
gas burner (slim like a flat panel tv?)
all interior lines (they put in a gas dryer too but not a gas stove)
changed from radiators to baseboard heating
they have a small 3 bedroom ranch that was destroyed during Sandy. they hope to get back in a few weeks!
Hope that helps a little.
Oh, I should add, the did contact national grid back in Nov to be put on a list and it was just done.