Is it essential that you get the 3rd edition? 1st and 2nd are on Library Genesis+ (from 2017 and 2021 respectively)
Otherwise, my university had some deal with Springer that allowed the purchase of a softcover book for 25€ (I think it increased to 50€ later), but also free access for the online edition (though not necessarily the whole book in a single PDF, but each chapter separately). Have you checked for similar deals at your university's library?
Is it essential that you get the 3rd edition? 1st and 2nd are on Library Genesis+ (from 2017 and 2021 respectively)
Otherwise, my university had some deal with Springer that allowed the purchase of a softcover book for 25€ (I think it increased to 50€ later), but also free access for the online edition (though not necessarily the whole book in a single PDF, but each chapter separately). Have you checked for similar deals at your university's library?