I switched from an oil burner to a gas burner a few years back - but I got the burner itself for free from KeySpan (promotional to encourage people to switch). I do remember, however, that the plumber's bill was about $2,300 just for the installation work.
Be careful, I now know that I got ripped off and could have gotten it for much cheaper. I didn't really have a choice because it was winter and my previous burner had crapped out and left me with no heat.
