It can give ROI if you  get to grab the first batch. Look at the people who got their hands on the first Dashminer. They were making almost $180 after electric bills each day. So to get your initial investment back, a month was enough. Even at a price 3 times higher, that would have resulted in an ROI in a months time. However buying now doesn't make sense, when Bitmin itself is selling it while eBay has been flooded by D3s.