Safe to buy from Ebay (UK) ?

I found the V20 on Ebay for £578. I would definitely buy it at that price, but something smells fishy. The same retailer sells it for both that price and for £650. The weird thing is that the cheaper version is actually Dual Sim? Any ideas why? The seller has 98.9% positive rating, but I am still not sure. What would you recommend me?

Check the "memory" amount. 16GB with dual SIM is cheaper than 32GB? (An additional SIM port and circuitry is a lot cheaper than eemc storage.)

As for safe, there's no telling - it's not eBay, it's individual sellers. (Although eBay seems to err on the side of the buyer.)