Best place for parts is nissan really or shop dealing with rack overhaul as fair few bits be same as lot of others.
What's wrong with rack, if just seals and bushing not too hard or expensive get bits from nissan, if everything well worn inc rack gearing then it tricky repair and donor racks complete or for parts likely needed .
I not done an R one but from previous hassle and costs on racks I tend favor sourcing A1 used or at least a used with good rack and pinion condition so a basic seal, bushings refresh gives better chance of worthwhile end result .