used coils are fine as long as you check them out first, Ive an old whites classic coinmaster 111 with a standard 8 inch coil, also I picked up a 11.5 inch coil for 50 quid (wiltshire detectors) and a generous guy gave me a 4 inch coil for it as well,,fab for trashy areas...only having a coil cover for the standard coil I coated the bottom of the other two with a bit of fibreglass tissue and resin then finished with a wax top coat, stuff I use in my job... brill protection for my coils....good luck mate try Wiltshire detectors if youre looking for good used coils etc.