If it's a simple ring adapter, it will either have a glass element in it to act as a short teleconverter, so you can focus to infinity, or you won't be able to focus to infinity (ok for macro and some portrait work)—that's why the eBay listing you found is for a macro adapter, and the description mentions you can't focus to infinity with it. You can probably focus out to 10' or so.
This is because the Nikon F mount is deeper than the Contax-Yashica mount, and if you hold the lens farther away from the sensor than it was designed to sit, you affect the lens's ability to focus through the entire distance range (think: macro extension tubes).
If you want to be able to focus to infinity and not have a teleconverting element in the adapter, then you're going to have to modify the lens's mount to shave the additional distance off the back of the lens. Or you could attempt to modify the camera's mount and reduce the distance, but that would be very difficult to do without destroying your camera.
The only commercially-available lens-mount replacement kits I know of for Zeiss C/Y lenses to Nikon F are from Leitax. And you do need to do some research that they have a kit for your specific lens. And, unfortunately, it looks as if the Planar 50/1.4 [MM version at least] is not compatible with a full frame Nikon (possibly due to mirror collision with a back element--this happens a lot with Canon 5D/6D bodies, too).
I know it's probably not what you wanted to hear, but I'd say if you want to adapt this lens with a simple ring adapter, get a mirrorless camera.
See also: Can I use lens brand X on interchangeable lens camera brand Y?
