re: How much should it cost to add a short 1/2" natural gas line ?

damn man its not rocket science, just add the pipe fittings and your done, home depot has everything you need to do it yourself

unscrew pipe under the tee, ad another tee and a short nipple and a shut off valve and then add the fittings you need to run it anywhere you want it, then strap the pipe to the brick with clamps and masonry anchor screws

i bet you spend less the $100 on the galvanized pipe and fittings and its just an hours work to do it

the pipe at the bottom is there to collect any water that builds up in the gas line so thats why its there like that