A used detector may be cheap at first but it is a more costly investment move
. Since it is already old and has been used for quite some time in the past, it may have some parts that are damaged already even if only slightly. With these, you could not look forward to a fun hobby. You may even need to visit a shop to have this equipment fixed. When this happens, you certainly would have to spend more again. If the damage is too serious, you may have to buy a new detector instead.