Here. (Scroll down to "Chain".) It costs $700 (AUD) for one bicycle chain; plan on using only 73% of that, if you want to stay within the cost limit.
Alternatively,
Tsubaki sells some (scroll down to "TI Titanium Roller Chain") that might just conform to ANSI specs. Contact any of their local distributors (on their site) for pricing and lead time. If I might hazard a guess, they're going to say that it's a special order with a minimum quantity, costs about $200 (CAD) per foot, and that they will need 14-20 weeks to process the order. You
might have better luck, but I doubt it.
While I'm in a Tsubaki state of mind, let me point you to their
catalogue, which contains a lot of good engineering information. Section 1, pages A-6 and A-7 (in Acrobat, 17 and 18) have horsepower charts for #25 and #35 chain; consult those--you might be able to get away with #25, instead of #35, if that's what you had in mind. That's a significant weight savings, if it can be done.