Price clarity and fairness
A comparable 20-page hardcover book costs £40 from Popsa and £32.99 from Mixbook, making Mixbook cheaper at non-sale prices. However, Popsa’s per-page cost for extra pages is considerably lower, at £0.69 per single page compared with Mixbook’s £1.29 per page, which only comes in double-page spreads at £2.58 each.
That gap closes the longer the book gets: Mixbook’s lower starting price only holds for around 11 extra pages (roughly a 32-page book); beyond that, Popsa’s lower per-page rate makes it the cheaper overall order. Both brands set the same 20-page minimum for a book.
The gap widens further on upgrades. Popsa offers a cheaper layflat binding upgrade, at £20.00 versus Mixbook’s £44. Paper finish defaults also run in opposite directions: Popsa includes matte as standard with gloss as a £0.49-per-page upgrade, while Mixbook includes gloss as standard with matte as the paid upgrade – so which finish comes "free" depends on which one you actually want.
If upfront price is your main concern for a shorter book, Mixbook’s lower starting price wins – but only up to a point. Add more than around 11 extra pages and Popsa’s lower per-page cost overtakes Mixbook’s cheaper base price, making the overall order cheaper with Popsa.