Nobody is selling the RX 470 mining cards for $250 - the NewEgg postings were mistakes, they don't even have the cards yet - and the rep I talked to was pretty sure they were NOT going to actually sell the things at MSRP or even close when they DO get them.
If you can get GTX 1070 at $400, GRAB THEM - that's bloody cheap at current pricing, and is the same ballpark they were in a month ago before the started getting impacted by the "mining caused GPU shortage".
Last time I checked NewEgg (yesterday), for example, the LOWEST they had a "in stock" GTX 1070 listed at was well over $500, and most were $600-$800 of the VERY FEW IN STOCK options they had at all.
BTW - they didn't have ANYTHING in an RX 470/480/570/580 for under $500 at all, and only 1 or 2 options under $600 - at current pricing the RX line has ZERO advantage in reaching ROI over the GTX 1070.
Trying to call those cards "$250 cards" is not valid and hasn't been for a month or two now.
The rep you spoke with is incorrect. The mining cards were in stock at Newegg and limited to one per person for $260 for the Samsung cards and $250 for the non-Samsung version. They are still listed on the website and you can sign up to be notified when they come back in stock.
https://www.newegg.com/Product/Product.aspx?Item=N82E16814202291https://www.newegg.com/Product/Product.aspx?Item=N82E16814202283This morning Newegg also had Nvidia 1070's for $399.99 and others at $429.99, limited to one per person. Several places have had the regular RX 570 4GB cards at less than $250 over the past week. You need to act fast because they sell out quick.
http://www.nowinstock.net/computers/videocards/amd/rx570/ I had one of the mining cards ON ORDER - and the order was cancelled "as the cards had not come in yet".
It would be nice if the RX series cards and the GTX 1070s are starting to drop back down towards MSRP - but I've not SEEN that to date, and the availability is still nearly nothing.