Older Camera bodies are generally not worth much at all, unwell it is a limited version of a particular model .
I own a Sony NEX5R which I still use and is great little camera. I still a 110 Halina, minolta x700 SLR, and late father 110 film Italian camera from the 1950's
There is a great joy in still using the older cameras just like looking a vintage old sports cars like TR4, MGBGT, escort Mexico etc
So my advise is keep them if their is no decent sell on value or use them when manufacturers offer a trade deal.
I keep an old battered car Hoover as Dyson now and then offer trade in Hoover deal against their latrdr hand held model.