Instead of trying to pin it to some standard of living metrics, I think its probably better to make it a multiple of the prevailing wage instead of the prevailing wage. If H1-B's are truly filling positions that companies cannot fill domestically then those workers should be worth far more than domestic counterparts. Companies should also be required to provide justification for rejection of each domestic worker that applied for the position.
These two things would probably fix the majority of the H1-B abuse, whether it results in more outsourcing is another question. But, large companies have data centers that need skilled labor to diagnose problems on site, be it SFP replacement or simply tracing cables. So i'm not sure how much of that kind of work can actually be outsourced.