Price hikes like this due to low availability makes me kind of wonder about those folks that do have cards that crap on them, if the manufacturers can replace/repair the cards in a timely fashion....
Makes me glad I have two 980Ti cards. If one does happen to kick the bucket, I still have a spare to fall back on.....then again, I see the price of used ones on ebay have gone up by around $50 since I last looked 5-6 months back. 980Ti cards are easily hitting $400 prices (some more, some less, depending on the card).
So, either folks are hard up for a decent gaming GPU since an equivalent card (1070) are more than twice the cost or these are just cheaper, decent mining GPUs that folks can still get their hands on.