So, you know how it says Feuilly “earned with difficulty 3 francs a day” in the Brick? Three francs in 1832 in today’s money, accounting for inflation, is $25USD (€22).
Given that labor unions were illegal at that time, it’s also safe to say he was probably working at least 6 days a week. 25×6×4= Feuilly made approximately $600USD a month (€529). The average one-bedroom apartment where I live is twice that much.
I also found out 3 Francs back then were also the average wage for 30 hours of work. Which, if you struggle with numbers, is more hours than there are in the day.
TL;DR: Tired, overworked Feuilly struggling to pay rent despite holding down so many jobs he doesn’t even have a second to freaking breathe? Canon.
Not to take away from Feuilly’s working-poverty situation, which is very real, but rent was probably the least of his concerns; cheap rent in canon-era France was very cheap. The rooms Marius rents at the Gorbeau house for thirty francs a year (and another 36 a year for the concierge to act as servant) are pretty bottom-of-the-barrel–shabby, with no fireplace or window. Feuilly makes more than Marius at this point in their lives; he most likely lives somewhere nicer. The grisette in Eugene Sue’s Mysteries of Paris, in the chapter @tenlittlebullets translated here (and which is pretty accurate on costs), is paying 12 francs a month for rent, and feels confident enough of her home to suggest herself as a model of economy–she’s going to be in a nicer little room than Marius has at the Gorbeau place, or may be paying for more furnishings, etc. Feuilly makes about twice what she makes; he could surely find a nice, clean apartment for one with an oven, and some sort of natural lighting, for a rent that wouldn’t be too painful to him.
(Also it’s very likely he would be sharing rent. Young men of all social classes had roommates; it was practical in a lot of ways!)
What’s going to be eating Feuilly’s lunch , economically speaking, is lunch –food was way more expensive, proportionately. Sue’s grisette spends 12 francs/month on rent, but 23 francs a month on food–and that’s only eating the cheapest vegetables, tubers, and bread she can get, along with “extras” like butter and vinegar–no meat, no sugar, no cheese, no coffee or tea, etc. Firewood and clean water would be another expense, and one that could get very pricey in the seasons when they were most needed. Feuilly is making about twice as much as the grisette here; he can probably afford his water and firewood without too much strain–but he’s going to have to be tracking every sous spent on food and consumable utilities to keep his budget intact. A friend stopping by with the equivalent of takeout pizza to share now and then, or offering to pay the concierge for an extra load of firewood while they’re there, would be helping him out a good little bit.
(It should also be noted re: Feuilly’s wages that he is a skilled, trained artisan at the point where we meet him–hence his slightly-higher-than-average wages. He’s certainly still working long hours, but he’s also going to have a few hours to spend in the evening, and is probably getting a decent lunch and dinner break at work, going by patterns in other shops. He’s overworked! but not 30-hours-a-day overworked.)
–All of which is just to say that yeah, canon-era Feuilly is absolutely living on a lean budget and likely worries about making the cost of necessities a lot! but his worries are likely to be less about rent, which would be a fixed cost for him, and fairly cheap at the time, than firewood, water, food and clothing, which were expensive and fluctuated. He can make it work! but it’s not easy.