I just returned from a trip from Holland to Niger. We did the Atlantic route, at Nouadhibou we drove along the railroad to Atar. Then Mali, Burkina Faso, Ghana, Togo, Benin and at last Niger. We did 5 days Air with guide, really nice.
In Agadez we sold our car, Toyota LandCruiser HJ60 Customwagon, for 3,7 million cfa. Around 5500 euro at a 665 rate.
Very little problems with the car, we started with a bad roofrack, welded a few times. 10 flat tyres on the road to Mali, after that no problem.
I was very surprised that at the border I couldn't get a Laisser Passez, and I just got into the country without anything.
Only returning from the Air the gendarmerie asked for the first time for the paper, I told it was at the travel agency and they bought it.
I always heard that the Feu de Route costs money to buy, but I heard from several sources in Agadez that it's for free. But only travel agencies can provide them.
If someone is interested in prices, routes or any other information I'm glad to help.