The internet/eBay is your friend here--there are many sources for simple changeout of the bulbs, just have to be sure the base is the correct one. I did all the lights on my old Suites and it made a dramatic difference in how long the batts stayed up for dry-camping. If you start buying at Camping World or some other retail source, it will get costly in a hurry, so check around and always take the old bulb with you to check the base.
Joe