High Impact Polystyrene is very similar to ABS in its properties (read more at Wikipedia), but works with different solvents (Limonene for HIPS vs acetone for ABS). Experiments are ongoing for HIPS as a support material due to Limonene not affecting ABS, and a similar cost (vs double for PVA).
*Reprap (30 January 2014) http://reprap.org/wiki/HIPS