The material is minimal cost for that diameter line and that isn't what you are paying for, it's the permit, the time and enough profit to make it worthwhile. Personally, I wouldn't want my neighbor to do it himself just because he "can". Usually they're the same guys that "can" drywall and "can" install flooring and when you put their work side by side to an actual tradesmans it's shit. Lots of people "can" do things and it'll likely work but it doesn't mean they should. If you're working with gas, get a permit.