As a former bike shop mechanic, I can tell you that the mark up on bicycle lubricants is huge. In fact, one of the main shops I worked for actually purchased its fork oil from the next door motosport shop because it was cheaper than buying bicycle fork oil at cost. So here are some helpful hints for saving money on lubricants.
Fork Oil-none of the fork companies make their own fork oil, they simply reliable existing product and then double the price. The next time you want to change out your oil, here are the actual products from a motosport shop. Remember that fork oil weight is not consistent from one company to the next.
Marzocchi 7.5wt-Golden Spectro Cartridge Fork Oil 125/150
Fox 7wt-Torco RSF Medium
Fox 10wt-Silkolene Pro RSF 10wt
Rock Shox-Maxima Racing Fork Fluid of equivalent weight
Manitou-Motorex Fork Oil of equivalent weight, Motorex 5w-40 oil is used for the semi-bath
Also, Mobil 1 ATF or Redline ATF is a good equivalent to Fox 7wt, Rock Shox 10wt, and Manitou 7.5wt.