Duel extruders

Hi,
I am in the process of rebuilding my i3 printer, and would like to add a duel extruder system, an anyone suggest one for me.
Any help would be appreciated, I have seen a few on ebay, but not sure if they are good enough. Thanks.

A dual direct drive setup is too heavy for the X-axis. Better try to add a second extruder driven by cable or Bowden tube. The second extruder could best be dedicated for "big nozzle infill " or printing support.
Be aware, that two nozzles are difficult to level properly. The unused nozzle will always scratch over the fresh traces and probably peel it off eventually.

There are extruders with a tilting or lifting mechanism, but I have no experience with them. ( Prometheus comes to my mind )

Consider the E3D Chimera. I have had good success with it. It's a bit easier to level the nozzles than with separate hot ends. Just bring the bed to within a half millimeter of the tips and loosen the set screws that hold in the heat break so both nozzles rest on the bed and retighten the screws.

Thanks Guys, will take a look at these.