I had the natural gas company run a separate gas line to the garage and install a meter. Around where I live they will run up to 100 feet of gas line for free and anything farther than 100 feet you have to pay $6.50 per foot. But they will do the job according to whatever the local codes are.
I had the same heating company that put in our new furnace and central air come out and install a “Hot Dawg” heater in the garage. They sold me the heater, installed it, ran the gas pipe from the meter to the heater, ran the vent out the back of the garage, and ran the wires for the thermostat. I had run a separate circuit for the heater when I built the garage, so everything was there and waiting for them to hook power up to the heater.
The cost for everything, including the heater, was a little over $1,900 which I thought was reasonable since they got the permit, did the work VERY professionally, and took care of everything. All I had to do was write out the check.