Smithy, I would compare it to other training schools offering programs, and see how it compares. If it still comes out far more expensive, I would ask them why they think their training school is better, and what can they offer you and your dogs more than others can?
I personally feel the longer an obedience course goes for the better. A short course doesn't always give great results for the average owner, whereas a longer course really can help you deal with so much.
If it was me, I'd be talking to them about your concerns, just as you have done here with us - their answers (or lack of) will tell you whether to go with them, or find somewhere else IYKWIM.