I always buy the OEM mats, not just for winter, but for general ease of cleaning, rainy reasons etc.
I scoured online for the appropriate part numbers for my 2011 M56, and copy pasted the part number for the black floor mats online to see what other sites would yield:
999E1QY001BE - beige
999E1QY001BK - black
999E1QY001GY - gray
They are
originally listed for $125 but I found them for $54 on this site called Newparts
https://stores.revolutionparts.com/genuinenewparts.com/(also might be affilitated to Partbull according to their phone prompts). With shipping the total came to $64.52. Fast shipping, but they sent me the wrong mats. Communication has been poor and resolution slow, so I opened a paypal case.
Meanwhile I jumped to this other site operated by
Grubbs Infiniti in Texas
https://www.nissaninfinitiparts.com/. The mats were $56.25 and with shipping the total came to
$69.44
Grubbs in turn had to order the parts from somewhere as they were out of stock, but shipping was quick considering the circumstances.
Good quality mats and are labelled M56 with holes to accept the factory hooks.