There are many phone, tablet and computer choices for today's consumer to select from. The biggest question after they upgrade or purchase their new device is always what do I do with my old one?

The global used smartphone industry is worth a staggering $5 billion. 

There are tons of sites online that will either buy your old smartphone outright or let you list your phone for the thousands of people out there not willing to shell out $1000+ for a shiny new iPhone.