Are you a collector?
If you are, put it away and forget about it for the next 50 years. It might be worth some small historical value around then to museums (if any are left by that time).
If you bought it to use it then use it.
Asking us the question you ask implies you are a collector and bought the Mac solely because you want the value to appreciate so you can sell it off for the highest possible price. Not knocking you for that, but PowerPC Macs are not the Apple I. They are never going to appreciate like that. Too many were mass produced and they are not rare.