What about these? You can get them heated, and they are already perfected?
http://m.dhgate.com/product/commercial-grade-olive-oil-press-machine/217082168.html#pd-019
The only thing i see being a problem is that this machine is designed for seeds it seems. Plant matter may gum up the works more so than a dried seed. I think one of the smart people on here mentioned some other smart people modifying one of those to work but I have no info to give other then that.
Would be awesome if it worked as well as it does with seeds.