YES! They are available, whether it be for Ski, Wakeboard, or Bikes. The rack is made by Thule. If you go to Infiniti Canada's website, they have these as optional accessories, I am not sure why they don't have them available in the US, but there are several Infiniti dealers in Canada that list them on their websites, including this company that is on ebay, shipping is very reasonable!
http://www.ebay.com/itm/INFINITI-JX-ROO ... 61&vxp=mtr
You must have the crossbars installed!