Hi bud
GW's plastic minis' modular design is so versatile now, you can pretty much fashion a great looking yet simple gang from the standard box sets. Check out imp guard and even space marine scout models. The only drawback to this is that the weapon options are pretty much limited to lasguns and the occasional bolt pistol. Have a look at
http://www.games-workshop.com/MEDIA_CustomProductCatalog/m1330067_Necromunda_Tactics.pdf
There are some great suggestions for conversion options for the existing gangs including using warhammer fantasy models. This might be a good starting point for your inspiration. I had a great time making really convincing Goliath gangers using chaos marauders.
Best of luck dude. Look forward to seeing what you come up with.