RVF400 rears show up on Ebay all the time, expect to pay around £250 (UK pounds) for a rear in good condition.

The MC28 front is narrower (3") than the RVF and I believe is an NSR only part, MC21 one is the same as the '28, I'm unsure if the '18/'16 is the same.

The 3.5" front on the RVF is shared with loads of other bikes, VFR400, CBR400, CBR600 of a similar era etc. and does fit the NSR (NSR discs will fit, O.E discs on the 3.5 wheels are bigger).
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