My wife and her friends are all into jigsaw puzzles. New, they cost around £10 to £15. At charity shops, they cost a pound or two. Sometimes you can but them on social media in job lots, costing £1 or less each. They are then swapped and passed around the gang, until everyone has done them.
Typically only 10% of secondhand puzzles have missing pieces, and even then, it is only one or two pieces. Experienced puzzlers don`t seem to mind if the odd piece is missing. Eventually, they all get taken back to charity shops. All in all, it is a cheap hobby.