I like the series, but I honestly don’t know that I can recommend it, particularly not for the asking price.
The main problem is that the Monogatari series is hard to describe.
It is a Japanese light novel series, which is already enough to put off some readers. I’d say that it isn’t a typical light novel series, but that isn’t necessarily true, largely because there is a fair amount of variety across light novels. It might be better to say it isn’t a stereotypical Japanese light novel series, while remaining visibly a Japanese light novel series.
It is modern supernatural, but the supernatural isn’t “normal” supernatural. “Oddities” are aberrations strengthened through human belief. There isn’t so much a “good” or “bad”, much less a singular big bad, it is just that humans interacting with the supernatural tends to lead to bad consequences even when nothing involved is “bad”. There isn’t much action, events are often resolved through conversation or deals. Even there, several events are more simply de-escalated or postponed.