The chips themselves are $1 qty 1. Remove the old chip, put your unlocked chip in its place.
From AliExpress, it'd probably be $2-$3 including shipping.
They don't ask questions when ordering large volumes of microcontrollers either.
If someone wants to get a hot air station and a bunch of $1 chips and reprogram their own devices, it would cost them less than a hundred dollars, 150 tops.
Anyone can learn any skill. If you can draw anything recognizable, you can do electronics.