"How do you think we could get the price down to $100/lb, gbaikie?
Fully reusable hypersonic scramjets?"

Generally speaking I would say Space-X is going in right direction, in other words, not hypersonic scramjets. And Space-X is not THE answer, but rather it's example of going in the right direction. Sea Launch is another example of going in right direction. Arianespace has been a helpful element; and Russia, and Chinese competition is a good thing. Lockheed and Boeing involvement with EELV has been good thing. NASA's effort to go to the Moon and beyond, and in particular if exploring the moon to see if there is minable water is not derailed somehow, is a good direction.
NASA's small effort in regards offering prizes is good step.
And finally the effort of making suborbital trips/travel available to public could lead in very significant way to lower launch costs- and rocket racing could a significant thing which is related to this.

Now, as far as my "bright ideas" as far getting to the time when we have $100/lb, I have two suggestions.
One idea is for govt or some non-profit entity to offer to buy water test payloads. The idea isn't for example to pay say Space-X to deliver a water test payload, but rather offer to paid any US launch company a set price [which is low price] for 100 tons or more of water test payload place in orbit and orbit must be one that allow water payload to remain in orbit for more than 5 years. These payloads can be any size [such as: 5, 10, 20, or 100 tons]. So, essentially, the US govt could say for next 5 or 10 years we will buy any water payload delivered to any orbit [which will last longer than 5 years] once this is done we will immediately pay for it [and US govt owns it] and for budgetary concerns we will limit the total volume we buy to 100 tons [higher quantity would better, but say 1000 or more tons could be excessive, 200 or 300 tons might good cut off point and 100 tons a being minimal amount or starting point]. And govt offers to pay $500 per lb of water delivered, so at 100 tons being upper limit, that's 200,000 lbs @ $500 per lb costing 100 million dollars with at most say 10% more to manage program: 110 million total cost. And if it takes 5 years to deliver 100 tons of water that's an average yearly cost of 22 million.
And finally, if one gets enough water in orbit, the govt could offer to give this water to any company that will "mine" it for use of LH&LOX rocket fuel [build with private funds a "gas station"].
If the govt did this, it would "make money"- in other words if govt spent in total less than the cost of one shuttle launch over a period of say 10 years, it would save in "other costs" well over this amount within that 10 year period [not to mention the years beyond this]. And if it this water is actually used as "payment" to build a gas station; then the govt could *really* "make" a serious profit- you know, in the range of billions to trillions of dollars in time frame of 2-3 decades. I would say as a SWAG every year delayed in not doing this type of program is costing the US tax payer at least 1/2 billion dollars [which is small potatoes, but it adds up].

Next idea. We need to lower the "launch pad" cost of rockets. At present, it costs millions of dollars just to have somewhere to launch a rocket which goes into space. So we need to increase access to launch pad- it should cost less than 1/2 million dollars to use someplace to launch a rocket. My idea of pipelauncher is one way of addressing this problem.