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I would go along and see it first, taking no cash, and only promising to pay for it after seeing it. Then, after you purchase it, check the box immediately to make sure you haven't fallen for the brick scam (where a brick is placed in the box to make it weighted, you walk away thinking you've got a Mac Mini etc etc)
 
Looking at the location it's probably in the newish apartment buildings there. You'd most likely be o.k. to take cash with you.

Looks a good price for the last gen. I'm hoping to get £400+ when I sell my mid 09 Mini (2ghz - 4gb -120gb). Though I'll probably go down the ebay route.
 
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