Just came across a company known as Secret Weapon Miniatures (Thanks TableTop Gaming News). They sell a really nice 28mm vehicle called the Rapid Assault Vehicle. The assault vehicle is 5" long (127mm) 3.25" wide (80mm) and 2.5" (60mm) to the top of the turret and retails for $39.99. I would love to see this in a 15mm version. The accompanying gun barrels look very cool.
Beyond the vehicle, they also sell a bunch of washes and weathering pigments.