Maybe you want to check out this site:
https://www.asicminervalue.com/ - it gives you real-time costs/profit for almost every miner thats available on the market.
Please make sure to set ur electricity costs right to get real values displayed. By clicking on a specific miner you get more details about costs/profits on various periods and if you scroll down u should see some shop options where you can buy them. Dont forget to calculate import taxes and shipping

To answer this question:
For Bitmain,
https://www.bitmain.com/ is legit. IceRiver has some fake sites, so be careful there. Their correct site is
https://www.iceriver.io/ - I can even confirm that myself because I just ordered there myself 3-4 months ago.