Where to get missing weapons for Warhounds from the Big Box?

As per title - the Warhounds in the box have like 1/2 of weapon options available. Missing are Inferno Gun, Mega Bolter, Turbo Laser, Plasma Blastgun, Graviton Eradicator and Conversion Beam.

I'm new to epic scale, so maybe thats a newb question, but any idea where to get them from? Can be GW, can be 3rd party.