Honestly I was abstracting combat to avoid the miniatures grid slowdown of D&D, but some scenes it definitely helps to have them.
I still have a handful of partha figs and the color cardboard standups that came with Shadowrun back in the day
Iron Wind Metals makes and sells the old official Shadowrun models.
Copplestone makes a bunch of corporate with guns models, themed gangs, and SWAT teams. http://www.copplestonecastings.co.uk/
Games Workshop plastics work in a pinch. Imperial Guard plastic Cadians can make good security teams or military obviously. Their Necromunda line has gangs.
Wargames Foundry has their Street Violence line. http://wargamesfoundry.com/fantasy_ranges/collections/futuristic/street_violence/
Corvus Belli has a sci-fi line called Infinity with cool drones and what could be troops in FFBA.