I wonder what kind of unmanned probes we could have by now if we didn't have to spend it on a military? If you don't have to worry about life-support and could afford redundant probes to deal with the risk of high-speeds, those things could be really fast, and we perhaps could be getting close-up data from the nearest star systems by now.
Sorry, not even close.
The estimate that I've seen for Project Icarus, which is one of the most thorough realistic concepts for interstellar exploration, was $100 trillion. (For comparison, global GNP is around $70 trillion, and US military budget is probably on the order of $1 trillion at most once you include stuff like the NSA - DoD alone is more like $700 billion. Some of which we do actually need for national defense.) That probe would have been unmanned and taken 50 years to reach Barnard's Star (only about 5 light years away), plus at least a 20-year development time. It required technology that, while theoretically possible, isn't even remotely close to working; it also required installing orbital infrastructure around at least one of our gas giants to mine the isotope(s) required for its particular flavor of fusion.
If we restrict ourselves to current-day or very-near-future technology, we might be able to get something to a nearby star in a few centuries for a much smaller sum. I'm totally in favor of starting work now, but I think the political will for spending large amounts of tax dollars on such a project is near zero.