Is N5 based on the Argentinian Maxi rally car? If so I would expect it to be a similar cost?
The RMC Motorsport website has a contact form with just N (R2, R4 etc) listed as car types.

As well as a construction/ purchase price, a running cost per season for the area/ events a competitor is going to take part should also be factored in a competition budget. (and all the other variable costs - sponsorship, event entry fees, travel/ accommodation costs, contingency fund for engine/ transmission failures) etc.