I've bought and installed used OEM alternators and starters from LKQ. Go on ebay and search "2006 Murano alternator LKQ" and it will show what they have in stock. I paid $80 for one with 96K miles and its been running perfect for 3 months now. Also bought a used starter from them 2 years ago.
They're cheaper than new aftermarket or questionable quality rebuilds. The only problem is that you are buying used parts so you must check them over very well for damage. The first starter I received had a broken solenoid from an accident, and the first alternator they sent me was for a GMC truck haha. They just refunded me and let me keep them, then I reordered and got the right parts the second time. A little headache but at least I bought low-mileage OE parts that will last a long time.