A single spellcaster, spending the majority of a working day casting the Mending cantrip, will repair at the same rate as a non-magical team of repair personnel.
Paul Gregorwich has a Pay What You Want with a suggested price of $0.00 on the DMsGuild for Monster Harvesting.
WotC also recognises that the designer community is worried about the changes. As a result, the plans to remove these individual titles from the DMsGuild have been scrapped.
DriveThruRPG, who work closely with Wizards of the Coast, had the books as PDF in DMsGuild for a while. This month, though, they've added the print-on-demand options.