I am a multi year User of diafine and also Xtol. Recently mixed my first batch of Barry Thornton two bath developer. The chemicals were about $40 shipped from PhotoFormulary and it will make six liters of both baths or about 100 rolls. Some people say that you can replenish and use it forever like diafine. There are several threads on this if you are interested to learn more.
Don't look at $/gal, figure out $/roll - that's what really matters. I believe Diafine basically lasts forever and the only consumption is via carryover.
You can also mix similar 2-bath devs from scratch for pretty cheap.
I agree. It lasts almost forever. In practice I found that it does eventually get "tired" and start producing thin negatives, or maybe this was because I never bothered replinishing a working bottle with fresh to top off per instructions, just kept pouring it back in the bottle. In any case though I found this limit was about 60-70 35mm rolls per quart. At the lower number that's eighteen cents per roll. I have a gallon I've been using for two years, and another gallon of powder on the shelf. As far as I know the powder should keep for many years since it's sealed in metal cans. I've been tempted to stock up since I saw the price going up. A couple more gallons would be a lifetime supply.
But if the price is really bothersome, Badger has it for $34.95: