As I recall, Charter began production around 1964. I suppose there may be some collector value in one with a low serial number, but not much. Like $200 for something similar and newer for $150. Charter did make some 20th anniversery limited edition models. Highly engraved and well finished .38 "Undercover" models. These would be of more "collector" value I would think.
Never heard of a Charter "Saturday Night Special". Though they may have picked up that name from the "anti-gun" folks since they were cheaper than the premium priced S&W and Colt small frame revolvers of the time.