as well as the ever increasing cost of nitro itself due to it's manufacture ONLY in China, nitro-based fuels and motors have seen a tremendous drop in popularity so it's no surprise that hobby shops don't bother to stock it anymore.
Nitro is not just made in China. And it's getting cheaper not more expensive. You can mix your on for less thant ten dollars. The low production and shipping rates are the reason for high fuel prices, not the cost of nitro or any other compnent.