200 feet of lead gouging is going to put your welding machine to it's limits- rentals are cheaper than replacing yours. If they're being that nice to you it's because A] they want your cheapest price or B] they really want an employee who will work for even less. If you need to ask pricing questions on this forum you are late for class, this is not a business forum it is a code welding forum. The business forum is over at the School of Opportunity and Hard Knocks and they are only available to answer questions the 3rd Tuesday of the month, when available, which they aren't usually and when they are they are usually wrong about anything they tell you.
How much do you want to make a week? Month? Year? Do the arithmetic, and if you're worth it, and you know it, then that's what you charge. Business is more about ethical profit than it is about friendships.
And yeah, make sure your insurance is up to snuff , covers your ass, covers the work you plan to be doing and don't sweat losing the work because you're too expensive. How many maniacs you think they're going to find for that kind of gig? Not me, you can bet your ass.
Too bad Cummins Guy ain't around he used to do this kind of stuff.