I had a unit in an indoor market for some years and next door was a Mobile Phone man. I did notice although his stall was full of cases on show he actualy sold very very few, he said they where displayed only to let people know he dealt with mobile phones, and in fact with regard to cases the phone models changed so fast he got them in to order. his main source of income was repairs, mainly screen replacement and sale of chargers and leads. His main supplier ( a wholesale phone company) also provided a service of repairing any thing he couldnt do. hope this info is helpfull .