I like to purchase used items off of Amazon to save $, but you cannot purchase used items through purse.io as far as I know. I've also noticed that the item prices are higher than the typical prime member pricing I see. So each time I've tried to use it, I found that I could get a cheaper deal in Bitcoin by either 1) buying the item used with a gyft.com gift card, or 2) buying the item with a gyft.com gift card using my prime account.
Purse only works with items sold directly by amazon therefore buying used items will most likely not work, although the savings from buying via purse is likely greater then the savings from buying used items via amazon. Although when buying via purse you are risking that the person buying is using a stolen credit card which could result in you being the target of a law enforcement investigation