I think the most expensive book I ever purchased I believe is The Art of Berserk for around a $100 due to tax and customs sinc eI ordered it from Japan. Also the book is put of print which makes it expensive. I do have manga boxsets, but these are multiple books so I don't think they account. So my most expensive books are art books.

35€ on feefal's art book and I think 30€ for Al Pacino's biography, translated, as a gift for my mom.
Most books I buy are old and generally cheaper.

Depends on definition of book. I have bought (and read!) the Encyclopedia Britannica. Was 7000DM, about 3500 dollar plus 40 years of inflation.

30$, only because it was the mtg books that came from the box, cards,,,etc. i only did it until i cant justify buying it anymore, since i dont play mtg after hs.

Excluding textbooks and technical manuals.

$300 for an OED dictionary. $60 for an illustrated book of poetry as a gift.

I spent like $100 on C++ books. Still got them, somewhere.

Personally spent? Around $15? Definitely between 10-15.

Most expensive book I have? Probably around $40-50 brand new.

I don't see any reason to buy expensive sets.

I spent about 4k on leather bound books for authors Brandon Sanderson and Robert Jordan

I'm curious what piqued your interest in this book. Was it an engaging read?

My most expensive is probably Dindal's Soil Biology Guide (1990), which cost around $300 as well. The print quality is pathetically bad given the price I paid, the spine came off only a few months after buying. Wiley Blackwell 🤢

X-Men #4 (1st appearance of Quicksilver and Scarlet Witch) ran me something like $4,000? I forget exactly.

https://gocollect.com/comic/x-men-4

I just spent $60 on a book that will probably cost me about $150 to get rebound.

Its John Dillon's "The Middle Platonist's" and its been really fascinating to read it as part of my desire to be educated on the history of Platonism and its eventual turn into a religion.

Its inspired me to start now a couple modern Plato clubs and I want to give my personal copy the love it deserves as the reprint is ass lol.

Here's a pic of it

The red copy is the library copy I was working out of when I first started Justin Sledges middle platonism seminar. The blue is The modern reprint and the page usage is atrocious lol. I can't wait to get it rebound and cut down normally

I bought a hustler from my friends older brother for $50 in high school.

I bought the Compact Oxford English Dictionary (the one with micrographic text) as a gift for a friend who was a linguistics major. It was also around $300.

Not one book necessarily but I've spent a solid number of bills on a shelf's worth of Headstamp Publishing books.

I bought the complete Calvin and Hobbs collection when it first came out in 2005 for $150

Not that much. Probably around $30-40USD at an anime con for a manga, not including the secondary one I got that kinda doubled the price.

Otherwise, for books plural, not me, but I am sure the Christmas gift boxset of a manga series I got probably around $100+USD would be the most expensive books I've seen purchased. College textbooks excluded.

A little over $100, for this book.

£120 on a pristine copy of The Biographical History of Electricity and Magnetism.

$30

Edit: No, wait. That's a lie. I had some expensive text books at university, but that doesn't really count.

I'd be really curious to know myself. Outside of college textbooks, I don't think I've spent more than 100 on any given book. Probably not even 80.

I can think of some art books that may have run me up into 40-70, like the Yoshitaka Amano book with FF work. Or the NES Ultimate guide from Contri. The Brawl in the Family comics in print probably cost over 100 actually, but then that's also 3 books.

I can think of a couple I've had eyes on that are pricey tho. The Art of Computer Programming from Knuth isn't rare, but a set would certainly be a nice, and costly, symbol of rigor I wish I had. Best Before (Newman) or English editions of Florent Gorges's Nintendo history books seem uncommon enough to be expensive.

I think about $125 usd for a biochem textbook