Suggest a scale

I personally would do all the spacecraft in 1/72 scale. Real Space Models has an entire kit for Mercury, Gemini and Apollo craft. They even have some aftermarket parts for a 1/72 Space Shuttle. I feel that this would probably be the most economical approach to your project. It really just depends on how much detail you want to place on your models.

While I would love to do these in 1/72 (my preferred scale for all models) this would be a very expensive undertaking. A more affordable option may be 1/200. I know this is an odd scale but AMT/Ertl did a kit with all 5 of the Manned Rockets called Man in Space. This kit can still be found (on ebay or this site has a few in stock http://galacticvoyager.com/cgi-bin/mod.cgi?id=03-218&c=040 ).
Never dealt with them so don't know about service (just came up first in Google).
Then you can either build the Hasagawa or Lindburgh kit of the Shuttle with booster and you are set. Should be able to do them all for under $50 (about the price of a 1/72 Shuttle without boosters).

Thanks, I was sort of leaning towards 1/72, but as I thought about it I also realized that it probably isn't appropriate to "everything" in the same scale, I have vague memories of trying to build a 1/72 scale lunar module when I was about 10, its probably what put me off modeling for the next 15 years

I looked at the real space site and with a little googling realized there is alot more available than I expected. As a kid I loved checking out the space models at science centers, now that I have a child I'd like to complete a set.

Thanks for the help.

Just wanted to say thanks for the help, I wound up ordering the 1/200 Man in space set and got a Hasegawa 1/200 Shuttle & boosters, the part that really sold me was when I actually saw the 1/72 shuttle kit, I'm sure its nice but I don't think the box would even fit through my door. My son is learning about the Planets in preschool so the timing is good.

I have to agree with most of the contributions already posted. 200 th scale is the way to go. AMT's Man in Space set is pretty good and Hasegawa's Shuttle with Boosters completes the line up. With a bit of casting and some appropriate scale tubing even a MOL Gemini or Dyna Soar can be added! I often see the AMT kit advertised second hand and perhaps ebay might get results, the Shuttle with or without boosters is available here in the Uk thorugh a few decent plaecs such as Comet Miniatures. They might even have the AMT kit. Good hunting!