Help Tracking down an optional rule

[jshelky]

Somewhere in one of the later 3.5 books there was an optional rule for purchasing a focus that could replace the material components of a spell. I seem to recall it having a price of 50 times the cost of the material component.

I'm hoping to track down the original rule, but sadly as I'm fairly certain it was hidden in a stray side bar and I haven't managed to locate it. And all my attempts at google-fu have failed as well.

If anyone can point me in the right direction that would be awesome.

Thanks,

 

[Abraxas]

The only thing I know is from the Netbook of Feats
http://www.dandwiki.com/wiki/Substitute_Focus_(3.5e_Feat)