Isn't it possible that if you do staged deliverable and fixed payments that this will mitigate the risk?
If you are able to specify the deliverables needed in enough detail, then you can make payment contingent of milestones. That way the outsourcing company gets a steady stream of guaranteed income, but it's continent in them completing the work. It also allows you to cross check the work frequently.
This, of course, means that you have specified what you need clearly and in sufficient detail that you can actually go this. That means though that you need a very technical lead who has the ability to do project management. I can't see how else it could work!
If you are able to specify the deliverables needed in enough detail, then you can make payment contingent of milestones. That way the outsourcing company gets a steady stream of guaranteed income, but it's continent in them completing the work. It also allows you to cross check the work frequently.
This, of course, means that you have specified what you need clearly and in sufficient detail that you can actually go this. That means though that you need a very technical lead who has the ability to do project management. I can't see how else it could work!