That's because there aren't any, at least not anymore. See this thread on Watchuseek for a discussion on the matter.
The only names you're going to find associated with the area (i.e. the Balkans) are for vintage/resurrected brands such as Darwil (Swiss, but had a facility in Trieste so in the Italian Balkans), clock (not watch) companies such as Insa (which mostly do gauges and dials now), and defunct brands such as Mestis (which appears to have used ebauches from Poljot and 1MWF).
Some suggestions:
Orient (especially the Bambino line), which can also be found on Amazon for somewhat less than list price, but there have been some questions about fakes of Orient being listed on Amazon
Island Watch has a number of listings in the U$50-150 range
Not with your very first Reddit post (or with a throwaway account) you don't. Plus, even if the watch in the very low-res picture is genuine - and I'm not saying it is; the picture is too low-res to make out any real details - how do you know it's not stolen?
Why bother asking? You shouldn't take this deal, and you know it.
Take it apart and use it for spare parts, because it's fake. Or use it for short-range small-target shooting practice (e.g. for airsoft).
*insert KILL IT WITH FIRE meme*
A little iffy on the cost, for what you get - which is basically enough parts for a single watch. For those non-sale prices, if you already know your way around the Miyota 82xx or even some of the cheaper Chinese movements, you can buy parts for multiple watches plus a serviceable tool kit (though perhaps not one from Bergeon).
This is true for all of those "assemble your watch yourself" kit sites. IMO you're better off buying the parts yourself, perhaps from a modding site (the one I linked is for Seiko and the listed prices are in Singaporean dollars, but you get the idea).
The price point is actually less an issue than how well-maintained it is (to a certain extent this speaks to its quality more than its purchase price), I think. Therefore an heirloom watch can be one at any price point, because it would be a combination of both sentimental and monetary value/functionality that makes it a "forever piece."
If you're smart about it and don't bid on literally everything that crosses your path, sure.
Marathon comes to mind.
https://miyotamovement.com/product/8215/
The official page for the 8215 says a "running time" (i.e. power reserve) of 42 hours. The spec sheet says "more than 42 hours."
The 8205 and 8217 have the same running time/power reserve as the 8215.
How obviously polygonal does it have to be?
There's also this monstrosity (definitely not thin).
This is better, but I have no idea how thin it is.
This article lists 10 reasonably-priced AP Royal Oak alternatives, but I'm not sure how thin any of them is.
Basically keep it in storage because of the thought behind it. If the gifter asks where it is, you can always say you're storing it because you don't want to risk losing it/having it stolen.
Over time/distance, you can get rid of it, use it for parts (my preferred method), or find some other means of disposal (e.g. target practice). If asked about it, depending on who's asking, you can say you lost it, or that it stopped working and was too expensive to repair so you sold it, that you had it customized (if you kept it and removed the unauthorized branding), and so on. If you believe the gifter can handle being told the brutal truth (or this is one of several gifts you've received from that person so one of them being faulty/fake is okay) perhaps at that time you can tell the person the plain truth.
As for fake watch disposal, for me it depends on what it's made of, what's inside, and where the unauthorized branding is.