I'm not sure how the firearm industry sets their prices - is it anything like the razor industry or video game industry?
Most companies sell the reusable product (plastic razor, game console) for a loss and recoup the losses on the sell of consumables (razor blades and games). Nintendo is the exception - they build cheaper consoles than Sony and Microsoft and can get away with selling for a profit.
Do firearm manufacturers sell their guns at a loss to recoup the losses in ammunition sales? Not really a question of particular political importance - just a subject I'm curious about.
It depends on the company...some gun companies allow their product to be sold via the traditional supply & demand model.
Companies like Glock set a minimum price for their authorized dealers irrespective of supply and demand. For example, if a big outfit like Cabela's has a huge backstock of Glock pistols, and could sell them for $300 and make a profit, they don't have that option...if Glock says "You can't sell these for less than $479", then the store has to abide by that if they want to remain an authorized Glock dealer. (unless something's changed since the last time I spoke with the Glock rep at Fin Feather & Fur outfitters)
When prompted for a reason behind doing it that way, he told me that it's to encourage buyers to go with the newest models...for a couple of reasons, 1st, because of profits (of course), and 2nd, because they make enhancements to their firearms with each generation and want the latest and greatest to be out there in circulation so that when people see a Glock, they're seeing the best possible Glock.
So in a nutshell, if a person's standing at the counter and their options are a Gen3 Glock for $300 and a Gen4 for $500, there's a good chance they're going to go with the Gen3. However, if their choices are the Gen3 for $479 vs. Gen4 for $500, the person's more likely to say "what the heck, it's only $20 more for the latest and greatest, might as well go with the Gen4"
However, as it relates to the OP, I don't see how allowing teachers to be armed at school would have any impact on "Guns making money" or school lunch programs.
If a teacher already has a license to carry, chances are pretty good that they own a gun already (which means the profits have already been made), it's not as if they pass a law saying "teachers can now carry", and suddenly millions of teachers run out to buy new guns.
...and as far as school lunches not making money...that depends on the district really.
If the school opts in to the National Free Lunch Program, they're prohibited from making a profit, even if a profit was technically possible. So it actually ends up being counter-productive to the cause of making the wealthy "pay a little more" as our president would say.
So the government subsidizes them for the needy students, but for the remainder of the students who are paying, they're not allowed to make a profit off of them. They have to sell those lunches for $2.25 a pop because they're not allowed to do anything better than a break-even...even if the other 90% of the students's family could (and would be willing to) pay $2.75 for the lunch...and even though that money could be used to improve the school in ways that would benefit everyone.
That's why some school districts decided to go the free market route and have begun opting out of the free lunch program by subsidizing the needy themselves, and in turn, allowing themselves to make a modest gain on their lunch supply investments and then turning around and putting that money to good use. They work with local food companies in order to buy food in bulk for a discount, and then price it in such away that they can afford to subsidize needy children, pass along a little bit of cost savings to the paying students (allowing them to buy it for less than if they were to purchase it from a store on their own), as well as kick a couple thousand dollars into school programs at the end of the year.
...obviously in a district with a 70% poverty rate, this solution simply isn't possible, however, in a district with a poverty rate below 20%, it's more beneficial to go the free market route for school lunches.