Walmart and Amazon host third-party sellers who offer "restored" or "renewed" units.
eBay and Swappa are good for finding lower prices from individual sellers, but you should vet their ratings carefully. Key Specifications iPod touch (6th generation) - Technical Specifications buy used ipod touch 6th generation
Sites like Back Market and Reebelo often provide warranties and professional testing. Walmart and Amazon host third-party sellers who offer