a fair price is what YOU want to pay!
I have a GS, so they are not fitted to mine and unless I picked up a set for $100, I wouldn't buy them.
I think I've seen them for $300 each. If you have an RSFV and you only need a couple of extras for spares, thats one thing, but if you want a full set of six, it will be expensive no matter how you do it.