Complete n-scale signal systems are beyond my budget. I also model in DC (DCC is more complexed than I desire) and finding or making a full operating DC based signal system is overly priced. Complicating the issue is that I am modeling SBB Swiss rail and I have found only one maker of this type. Laws of supply and demand means they can charge high prices... and they do. A 2 aspect signal goes for about 30 dollars US.
Like impressionism art, I believe that a simple signal system, a token green/red (2 aspects) will satisfy the viewer. There are also real uses of 2 aspect signals used in swiss rail, so using them is valid. You can see 2 aspects in use in the above video.
Some modelers act as if it is a sin if something is NOT complete like a signal system. Believe me, impressionism has been in use since the dawn of time. Just take a look at ancient Greek and Roman arts; and if that doesn't convince you of its validity... look at Hollywood movies. Even the hardcore modelers eventually have to draw a line at how much of their model is real, working, or how complete something is. That line is different for everyone. So I choose to keep my signal system simple (and fun).
