If we think that corresponds to about $100, then we are saying that the very nice prepared meal is in the $400 range. That's quite expensive for an 800 calorie meal.
Warning: gets a bit divergent and philosophical.
I think you're going about it a bit backward; the "meals" implied in DF are an abstraction needed by the sim so that they aren't constantly going back and forth. So, if you think of it as a month's (or whatever) worth of food, it's a bit more sensible.
In the real world, I think most people are exposed to somewhat over two orders of magnitude of meal cost, with outliers that stretch it to three. For instance, in the US to someone of a typical class, a poverty diet that manages to cover all the nutrition requirements for a day might run $1, whereas a really nice special occasion dinner out might cost approaching $100. In a cheaper economy or with efficient bulk logistics the poverty diet cost would drop down, and there are certainly restaurants that charge well more than that, so $0.5 to $500 as a less common spread isn't unreasonable; three orders of magnitude. So, in a world that doesn't have magic, or fantasy animals, etc. having an expensive meal cost 1000x what a cheap meal costs is reasonable; and when you add elaborate exotics it could logically go up even further.
The difference is, for most people who are not *very* rich, they don't eat the most expensive meals for a whole month; imagine what the astronomical cost would be if you ate only at Michelin-starred restaurants for your entire food requirements for a month. Whereas due to the way DF abstracts things, an expensive meal is an expensive entire month.
This isn't to say that the DF food system isn't out of whack; it certainly has issues. However, it's not as bad as it looks at first. Most of the problem is on the other end, crop production. And this gets into what is fun vs. what is realistic. Historically, the vast majority of humans have been engaged in the business of producing and processing food for humans.
Growing the Land has some interesting info; while based on the US which due to various reasons biases the number of "farmers" upward...
1790: farmers are 90% of the work force
1840: farmers are 69% of the work force
1890: farmers are 43% of the work force
1940: farmers are 18% of the work force
1990: farmers are <3% of the work force
The nominal default cap for a DF fort is 200; and many people have issues of running forts that populated. It's pretty clear that even semi-realistic late medieval (pre-1400ish) ratios would not be fun for most; perhaps having in a full fort of 200 something like 50 young kids, 75 farmers, 25 ranchers, 20 food processing (brewers, threshers, millers, cooks, etc.), 20 fabric processing (spinners, weavers, dyers, clothesmakers, etc.), and only 10 people to cover the "overhead" which is the cool stuff: sheriff, baron, cleric, scholar, blacksmith, carpenter, maybe a man-at-arms or two, etc. Now, as a resource-extraction town, you could do better; mining towns didn't have enough farmers to feed everyone, but depended on selling their products (metal, stone, etc.) for the surplus of other, more agricultural towns.
So, it's clear that 90% of the population to provide and deal with food isn't fun. And that modern-ish 5% to 10% is stretching disbelief a bit too much. But where in between that is the best? It's a genuinely hard problem.
My personal opinion is that I I usually prefer forts that are at least mostly self-sufficient on necessities (ie, not selling giant corkscrews for food from the caravans, or whatever); and that I want no more than half the fort to feel like "overhead", yet less than say 20% - 25% feels cheaty. So, I'd want to adjust things so that one farmer raises food to feed 5 to 15 dwarves, perhaps, plus an egg industry and some meat. Say, 25% of the fort producing or processing food and drink, another 25% producing clothes, weapons, armor, doors, beds, and so on, giving 50% to cover miners, military, and so on.