So I've been reading the forum and this is what I found. Hope it works as a guide for someone in the same position as me.
1) 12vDC Onyx
2) Solid State Relay (DC-DC). 30amps or more. Good option: SSR-100 DD DC-DC 100A if you can afford it, Crydom is better.
Don't use standard Relays, they produce huge amounts of EMF when the coil energizes and de-energizes, and the PWM coming out of the RAMBo will beat the relay to death.
3) 24V DC Power Supply. Good option: Meanwell Power Supply 24V DC 750W 31.3A
Spoiler with not to do stuff (learning curve ):
UPDATE: Thank you dpmacri!!!!
This is how I have it all wired:
Jan 09, 2016 Update: Hi, just to give peace of mind to people willing to buy a Fotek.
I've been using a 100a Fotek SSR for almost a year and it's all good. It doesn't even get hot while printing.
If you do make this upgrade, please share.