I have to second what Paul said. Especially if you are missing a lot of the parts, a good set of original style shocks can set you back a grand. However, a good set of tubular shocks can be had for less than $300.
Personally, I can strongly recommend the set from Ken Davis. I put a set in my '30 Coupe about six years ago and absolutely love them. Admittedly, they are a little stiffer than the originals, but they work great.
http://www.kendavismodela.com/Shocks.html
Good luck,
Ken