If you are close to a NAPA parts distributor, I would check them first as they almost ALWAYS have the part I'm looking for, or can get it shipped in rather quickly. It looks like you have found a good source on eBay for OEM style replacement condensers that I assume are a proper fit. I wouldn't worry too much about getting a genuine Nissan part as all the condenser does is cool the refrigerant via heat transfer with no moving mechanical parts.
Another thing, bookmark this thread...
http://www.zilvia.net/f/showthread.p...t+part+numbers... that has an EXTENSIVE list of interchangable Nissan part numbers and there you can find the A/C compressor V-belt part number.