As long as it is a factory lock you can buy replacements directly from mcgard. All you have to do is email their customer service with a good clear picture of the lug nut and they should be able to match it up. The one from my saleen went missing a few years back. It was in the console and then it was not. I emailed their customer service and got my replacements shortly after. I bought 2 just in case one goes missing again.
You can get the same parts for less then $300 if you shop around, I spent around $180 the last time i I replaced a tank on one but used a cheap kemso pump...
walboro is about $60 more give or take... You can get a new tank for less then $ 100 with taxes and shipping these days, sending unit for 30 ish, filler neck gasket $10.... Amazon has most of the Dorman line marked down pretty cheap right now