The N prize caused me to look this up

http://vpizza.org/%7Ejmeehan/balloon/

http://www.balloonsdirect.com/weather_balloons.htm

A dense paper about launch regulations:

http://www.colonyfund.com/Reading/papers/NH_rocket_contents.html

some more
http://www.seanet.com/~ssstolt/regs/faaregs.htm

the real thing:

http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr;sid=411c0579c5834b8dfae3aee3e75392dd;rgn=div5;view=text;node=14%3A4.0.2.9.9;idno=14;cc=ecfr

seems like the rocket has to be guided to allow a predictable orbit, thats tough.

some mass ratio calculations assuming 1-4km/s exhaust velocity and 7km/s orbital velocity.

? exp(7/4)
%8 = 5.754602676005730436866499705
? exp(7/1)
%12 = 1096.633158428458599263720238

Sweet they only put actual vehicle costs on the budget not the more costly licensing and other bureaucratic issues. Somewhere I found mention that launchers actually don't make such a large portion of the launch costs but all the other stuff like range operations.

Exhaust speed obviously matters. Here is a nice table for engines

http://en.wikipedia.org/wiki/Spacecraft_propulsion

High exhaust speed requires difficult to handle fuel, consider staging. Staging might need even more control systems and structure and drive up the price+weight.

http://en.wikipedia.org/wiki/Multistage_rocket

High altitude thrusters seem to be simpler.

Here is a starter book for liquid engines.

http://www.risacher.org/rocket/

Liquid oxygen might require insulation, more weight added.

More engines:

http://users.cybercity.dk/~dko7904/motor.htm

a practical one:

http://pages.total.net/~launch/ss67b2.htm

giving 0.8 km/s ve.

You will start at zero g what will do that to the fuel?

Enough for today. Zzzzzzzzz...

Another day has begun.

The Nprize group had this to say about SpaceX - snide bastards:

http://groups.google.com/group/n-prize/browse_thread/thread/0b5284d796c13a07#
http://ntrs.nasa.gov/search.jsp?R=891228&id=1&qs=Ntt%3Dsp-8056%26Ntk%3Dall%26Ntx%3Dmode%2520matchall%26N%3D0%26Ns%3DHarvestDate%257c1

The Introduction states: There must be no recontact between the separating bodies, no ...
38 years is a lot of time to forget something.

The idea with the cannon as last stage should be silly since most explosives don't store much energy
http://en.wikipedia.org/wiki/Energy_density

also the acceleration is nasty.

Have a look at this:

http://www.theonion.com/content/video/warcraft_sequel_lets_gamers_play