Have you seen the thread below on range hoods for an NXR?

AFAIK, Costco does not sell the propane conversion kit, although it is available from dealers like Dvorson elsewhere for about $80. Depending on your local codes and how handy you are, you could do the conversion yourself or pay a plumber to do it for you.

If you are anywhere close to Tampa, I'd say buy it from the dealer there and have them install the propane conversion kit. If you want the center grate, you can probably get a break on its price, too.

Maybe Nunyabiz can chime in here because, IIRC, he bought his natural gas NXR from the dealer in Tampa and was pretty happy with the service.

Here is a link that might be useful: Rangehood help for NXR?

As usual JW is totally correct.
The place I bought from in Tampa was "DKAdistributing".
They seemed pretty nice to me, had no problems with them at all.
We actually live in North Carolina, but at the time the place in Florida was best for us because we had friends that lived in Coco Beach, so we planned a trip to see them and made a detour on the way home.
Was a small place, nice people, and we got the best price around from them at the time.
Was $1799.00 delivered.
I was happy with them and would buy from them again if I were in the area.
The name of the woman we dealt with was "Vicki W Albert" cant remember the guys name for some reason.
(probably because I just had a bottle of wine with dinner, its my Bday).
Drop by see if its the same people.

Here is a link that might be useful: DKAdistributing