Well it depends how you want to get there.
Running the numbers, you need at least 1 MJ/kg to get past the 100km limit into what's officially considered "outer space". That's only factoring in Earth's gravity.
If we could do it with purely electrical motors, then assuming you pay 20 cents per kilowatt hour and only have a conversion efficiency of 10% into actual lifting power, it would only cost you $0.60/kg energy-wise to get up there. Assuming that you'd need to take an environment of, say, 10,000 kg with you, the marginal cost would still only be about $6,000. That's something of an ideal case, the "space elevator" proposal.
Solid rocket fuel, the numbers are a little harder to come by. It sounds like the active ingredient is usually aluminum. One page on Wikipedia suggests that aluminum has an energy density of 31 MJ/kg (and my calculations based on Wikipedia's "aluminum oxide" page agree) and that only 16% of solid rocket fuel is aluminum. So that's 5 MJ/kg. Or roughly 4 MJ/kg if you take into account that the fuel more or less has to push its own way up with you. (Not all the way, of course, but I'm too lazy to do the calculation properly and there's wind resistance anyway.) The first rocketry site on Google says that they'll sell you 20 pounds of the stuff (9 kg) for something like 200 bucks, or $22/kg. With the conversion factor of (4 MJ/kg fuel)/(1 MJ/kg lifted) = 4 kg lifted / kg fuel, the equivalent number is about 10 times higher -- you $6 per kg that you want to send into space, so the marginal cost is presumably then something like $60,000.
Can we do better by bulk? Google says people sell the main ingredient -- ammonium perchlorate -- at $3,000 per metric ton. Aluminum is a bit pricier, but I can find people selling large chunks at about $500/50kg, adding about $1,500 to the above. Adding in the cost of the plastic binding, the raw fuel components might cost $5/kg. So you're not going to get cheaper with rocket fuel than around $15,000 per flight.
Of course, the spacecraft is going to be the more expensive bit, I'm sure. But that's more complicated because maybe you can share that cost over five successful runs before it accidentally kills someone dramatically and no one buys it. I'm just saying that, even without that, based on fuel alone, it's still going to be an order of magnitude more expensive than a trip to a far-off land.
But these balloonists have the right idea. If you could instead send up a camera, you could potentially get up there at a fraction of the cost, something that hobbyists can do. "You know where this hat has been?" you could say: "OUTER SPACE."
(Incidentally, getting to the height mentioned in the above article requires only about 0.3 MJ/kg, so divide all the costs by 3. The 100km distance is where you're officially in outer space as internationally recognized.)