Brush 4 Hire do some fabulous tau scenery. What really impresses here is that you can select the colour of the forcefields … to match your Tau Sept. Really nice touch. Their bunker looks really good, though if you like a very rounded look for Tau, it might be too hexagonal for you.
And here are their matching barricades (or Aegis Defense lines!)
Scotia Grendel have a range of scenery that seems perfect for Tau – their NBO range. Here a couple of examples.
Micro Art Studios have a fabulous Tau Ceti line of scenery that would work fabulously for Tau. Their defence line looks awesome:
But their general scenery would really make a Tau board come to life.