The kit sounds like a decent deal, there are enough redundant pieces in there that you could part out a fair amount and lower the net cost significantly or finish out the kit to suit your needs better. But, its only a deal if if it fits your needs.
I enjoy my RB but it doesn't suit all my needs so The questions I have for you are "will the RB suit your shooting style or would say a TLR or Speed-Graphic fit you better", and "is it a style that you really want to explore?".
As to selling the Nikon kit to finance it, tough call.