You may want to make an ISO 9-6 post in one of the two Facebook Northern Lite Owner/Enthusiast groups. They typically let folks in the research phase of purchasing a NL join. Always somebody on the edge about making a decision to sell. Your post could bring them out.
Sales of NL's have increased quite a bit in the last few years. More times than not, used, late model NL's can be found on rvtrader.com; however, the vast majority of these will be located at dealerships. Older NL's in good shape are scarce. IMO, you'll need to keep your search nationwide if you want to find something sooner rather than later.
Good luck!