There must be a minimum that everyone agrees to accept.
For a guy livingin Almeria
Just for the bike, you will need 2 sets of tyres and BibMousses. Let's say 1.000€ (and that is cheap).
2 transmission kits, 300€. Oil and grease, 100€. New wheel bearings and filter 100€.
For the bike as a minimum of 1500€
Entry fee (lowest) 850€ + Visa arrangements = 1000€
Trip back from Dakar 400€ + Trip to Nador 140€=540€
Shipping motor from Dakar 400€ (????)
and the list goes on.
I think that you will be easily above the 5.000€ and only for a very basic set up