i have bought back ups of items before...
two were denim pieces (a denim romper and a pair of jeans in a flattering cut).
the jeans were awesome because i wouldnt have to tailor them to be made shorter (i'm petite) the romper i wore once a week during a summer when the average temps were 85+. i was obsessed with it...both rompers are still in great condition.
the original jeans i wore so much that the crotch ripped out and other parts of it became distressed....so i'm thankful for the backup. the original jeans i had mended of course. there's no way i'm going to get rid of them.
and i'm also thankful because of the designer of them is in precarious health and is not active these days.
and its almost time to break out the romper again...
even though i might be a tad too old for a romper.
my advice would be to someone that wants a backup is to create an ebay alert for the item. that will help you make up your mind in a few months. if the item is cheap enough it and on clearance, grab it i say.