The bigger problem with pentests is not the current cost but, as I see it, is that security is inherently and inescapably expensive somewhere in the chain, and that vendors have been getting a free lunch for too long. The viability of security analyses/pentests will go down if your goal is to reduce the cost by an order of magnitude because the people who are any good will find something better to do--and the consumer will still pay through all the bullshit externalities.

Security needs to cost to demand talent. The real solution to this problem, I think is that failure to secure needs to cost (whether in monetary or criminal terms) or it isn't relevant to business concerns.