A 30 Kiloliter tanker truck is not something I feel comfortable handwaving.
Oooooooooh.... you're trying to do it as a
commodity, not just fueling personal vehicles. That's the kind of thing you need to mention up front, man. Not only are the prices different when you get up to "by the tanker" sales, but your examples indicated you were looking for "at the pump" rates.
Still, either way, I'd just ball-park it to a nice round number, since I seriously doubt this is happening through legal channels. Makes adding and subtracting for Negotiation hits easier, too. Figure about 150,000¥, retail, for automotive gas, 200,000¥ for "premium" auto-gas or normal aviation gas, and 250,000¥ for "premium/jet fuel" av-gas.