Been thinking about this for a while now...
The only real impractical thing I see with this is getting the board users together in one spot at a specific time.
Virtual organization. The development and design of the systems does not have to be done together physically. There is software that allows teleconferencing, telepresence, etc. to allow collaborative work.
A lot of equipment and components can be bought COTS (Commercial Off The Shelf) even mil-spec and aircraft grade. Custom parts and assemblies can be designed ACAD drawn and sent electronically to precision fabricators and rapid prototype companies for production of hardware to be shipped for assembly.
Yes somewhere there will have to be a facility for the parts and materials to come together. And there will have to be bodies to do the work. But skilled and experienced contractors can be sourced for that if there happens to not be members with those skills available.
For the first part, before you get started at all, you're going to need a source of income (and thus, a job) and a lot of patience. Without a steady source of income, the project wouldn't ever leave the ground.
Capital. Venture capitalists, "Angel" investors, even advertisers, or a good old fashioned IPO. There is always money looking for new ways to get grown or lost. With the current financial crisis in the equity markets, there are literally Trillions of dollars sitting idle right now.
Next, you need a basic education in physics, chemistry, and rocketry if you want to get the project done effectively and efficiently.
There is quite a depth of knowledge on this board and readily accessible on the internet. With a little bit of publicity and exposure, it may be possible to recruit or at least tap into a very wide base of volunteer information and expertise.
Then you may want to move on to engines... Once you've got the engine running, you could then attempt to pack that into a container (the rocket's body, with all the fins and stuff)
Think bigger and think outside the cylindrical explosive thing.
There will be fixed costs associated with this project that will be the same if you are building a sub-orbital sounding rocket or a Saturn V. From the time you spend thinking and working on plans, to the cost of shipping components together, these are opportunity costs that will be nearly the same regardless of the scale of the project.
Also you will not be able to attract the requisite financing to do
anything bigger than a model rocket unless you can offer something new and unique. That means manned. That means reusable. And that means scaleable to something commercially viable.
Besides, I think all of us would like our chance to go into orbit. Not just someone's pet hamster.
If things work out, you could then start scaling up, slowly but steadily reaching your goal of 100km.
Yes. I'm inclined towards building a 1-3 person small lifting body with a scramjet with a secondary rocket engine to get it up to operating speed and to throw it all the way into orbit. To get to high altitude, it is towed from the surface by a lear jet like a WWII glider.
The orbiter has landing gear and is built of carbon composites, aerogel, and ceramics to be heat tolerant and low maintenance. gas and go.
Best of all the concept is scaleable. Build a bigger orbiter and tow it with a 747. Want bigger yet? use the big Antonov 225.
Where there is a will there is a way.