Ah. Gas explains the cost of the tank I guess. When we replaced our leaking NG unit we opted for an electric since we could get one so inexpensively and use it rarely.
I'd still be tempted to try it myself. The plumbing is already in place, and with a liberal coat of thread sealant the chances of a leak at the connector are small. NG has the advantage that if it does leak, you can easily smell it. Perhaps simpler than an electric, although it's easy for me to say since I haven't done one. Good luck.