I don't calculate like this.

I think that the most expensive device is the device that you don't use.
For such a device 1$ is too much.

Every device loses its value with its age.
If you have used it intensively it was a bargain.
You have to calculate the amortisation.

I will never give away my n900 because I don't know if there will ever be a device of quality open like this.

It seems that Nokia changes to more commercial software (even though Meego is more open than Maemo).
It seems even that on top of Meego there will be more commercial apps and Meego is better designed for that.

I think that the good time of the n900 will never come back.

I've bought my n900 for half of the price. (used 1 week with warranty).
Every dollar was worth its price until today even if it is cheaper today.
But I could use it until today and that's also worth its price.

And even when the n900 will be completely amortized the idealistic value will be so big to me that I will never give away this exceptional device.
This will also be the best way to keep the memory of my settings and dates.