When it comes to actual replacement fees, there’s more than just buying a new copy. I mean, hey, sometimes a library decides not to replace the thing that’s been lost or destroyed. Maybe the item wasn’t circulating all that well anyway or it’s a dead technology (i.e. VHS and microfilm and goddamn laser discs) that the library doesn’t want to keep in stock. Perhaps the patron will just pay a set fee that the library has created a policy for in the event of loss/damage. It’s all up to that particular branch, baby!