$200 doesn't sound too bad since you said you had your drive belt replaced, but generally it should only be less than $100 if you have it done by your local mechanic for just the oil change and replacing the cabin filter. Actually it should be around $50 or less if you just have the oil change as replacing the cabin filter can be done by yourself.
The cabin filter is about $20 from autozone
I just changed the oil on my 2013 Altima. It's a bit messier than doing it on my 2012 Beetle because the Oil Filter sits sideways and when you remove it all the oil gushes out. Plus to get to the oil filter you have to remove a couple of plastic rivets in order to move the plastic side cover on the passenger side in order to reach the oil filter. But they come out very easy and it's no big deal. Mobil 1 0W20 Full Synthetic Fuel Saving Motor Oil along with matching Mobil 1 Oil filter. $32.99 at Advance Auto.
Time to change the oil about 20 minutes. The dealership will probably charge you more plus they don't use synthetic motor oil which I prefer.
According to the manual the recommended Oil change interval is every 3750 miles which I think is an odd number even using conventional motor oil. I would say you can go at least 7000 on Full Synthetic some say up to 15k but I don't take that chance especially on the toy oil filter the Altima is using. The oil filter on my Scooter is bigger than the one on the Altima. When I first saw the oil filter I thought it was a joke. But I guess it works well enough for Nissan. Anyway, I guess if you are using a conventional Oil or Synth Blend I would change it every 4000 miles if you use a full Synthetic I would change it every 6000-7000 miles.
Oh, the recommended viscosity is 0W20. If you use a heavier weight oil you probably get less gas mileage.