Re-sale value never even crossed my mind tbh. The whole car is a toy, a gift to myself after lusting for years (despite having to use it every day) - so, having the colour and spec I wanted was more important than what I might sell it for.
As I can't afford more spare cars, and it isn't band new, I'll drive it as much as I like till I want or can afford a different one. It'll have been looked after as best I can manage and will hopefully get a good price - I am not sure nav will increase the value much, but it is nice to know it will increase desirability therefore it should sell faster. Especially if I 'invest' £100 in the most up to date maps I can run in the system before I sell her.