Buy it for Life

The encore has 40 grind size levels. It is literally an espresso grinder.

Um lol no, it doesn't work like that. Doing 40 or 400 or for that matter stepless is mechanically trivial in a grinder. If that was all it took, nobody would buy Kafateks.

best entry level brand at this price. You will only be disappointed by comparing it to machines multiple times the cost

That doesn't sound BIFL to me, if you buy it today and then upgrade to a better one when you can afford to. While not being absolutist, BIFL to me means that you have a reasonable expectation that it is the last one that you are ever going to buy. So the gear has durable enough to last that long, and good enough that you feel that it will always meet your standards.

Do you know what the difference is? Between a general purpose grinder and an espresso grinder?

Yes, OP didn't ask about espresso at all. Espresso is a huge money sucking rabbit hole that I wisely(?) avoided entering back when I was into this kind of thing. It's a permanent upgrade treadmill. I have several aquaintances with Kafateks, Lyn Webers, machines of the week, lab instrumentation, microscope photos of coffee grounds, etc. I decided not to care. Once in a while I go to the local cafe and have a Slayer shot and I'm satisfied. I don't have to be able to do that at home.

As for the Encore, well, you've had a dozen broken ones in your shop. I'm not an abusive or especially heavy user and I've broken two of them myself. It's an ok grinder but BIFL doesn't come into it, it just doesn't. It's nice that you can get repair parts from them today but do you really expect the company to exist (and not be absorbed into some evil conglomerate) through your entire lifetime? The Forte (Baratza's semi-commercial model at around $800 new) might be a plausible BIFL grinder for the average person. Basically you want a grinder made for commercial or industrial duty, so its service interval (however many thousand pounds of coffee it is supposed to grind before needing major repairs) is larger than a home user is likely to use in their lifetime. If I had unlimited funds I'd probably want a Kafatek, but mostly because I think they are cool.

Baratza was founded in 1999. Do they still sell repair parts for the grinders they were making in those early years? The part that failed on my second Encore was the burr collar, a weird shaped piece of plastic that probably can't be gotten anywhere else. Maybe I could 3D print one but that's beyond the call of duty.

Also don't forget that lots of Encore users like to upgrade the burr to the one sold in the next higher (Virtuoso) model. I never bothered doing that with mine.

The OP was asking for a BIFL grinder with a maximum budget of $100.

Yes and I'm asking for a flying pony. I think it's best to give a realistic answer, which is that what they are asking for does not exist. That happens in every area of life and adults are supposed to be used to it and not get upset. There's a Bunn G2 on Craigslist right now for $275 and that's totally BIFL after a mod or two. There's also a G9 for under $200 but my coffee nerd buddies advised against that model. We don't have to be like AI chatbots who tell hapless humans what they want to hear even if it's nonsense.

It's not completely impossible to keep it under $100 if you see something that is being thrown out from a restaurant or whatever. But that's a matter of luck.