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The seller has 100% feedback from over 100 users, so I'd say it's rather safe. As for price, since it's a sealed brand new Mac anything below the price you can get from Apple directly (which the seller kindly included in the photos) is a good deal. Check a few other places that sell Macs and see how much this same model is. If it's less than the Apple price, then don't bother if the bidding goes above that price.
 
I just did the conversion from British Pound to US Dollar. 1305 British Pound is equal to $1941.12. Yikes!! That's crazy expensive. I believe the price increase is due to the 512GB SSD.

I'm not sure of the price differences from where you live so I can't comment if that's a good deal or not. I purchased mines with the same specs minus the upgraded SSD and paid $1500 (a tiny bit higher). I think original would have been a tad over $1700 but I got a University discount.
 
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