Hi Edoardo! The printer-friendly version isn't really just a low-ink version. Printing in booklet format would involve taking the singles version and doing some rearranging of the pages. I'll look into how complicated it is to whip up a booklet format version and add it to the downloads, but to be honest, the whole thing is designed to be full-bleed so I worry about things getting cut off or the font size getting really small.
We do have print copies available if you want to buy one, though — people who've purchased the PDF get a discount.