The wheels are metal Irregular Miniatures from their Useful Range Artillery. The central control box is a piece of styrofoam (don´t forget to protect it with a thick coat of PVA glue before spray, or you will get a really small box...). The ladders and such are metal.
The Radars themselves are Made-in-China toys and most of the details are the trustable Evergreen plastic tubing, sheet and rod along with other styrenes.
This is the way how I produce quick reference for scratchbuilding: Google + attach images to word page + print = that´s it.
Try to capure images from the best angles and particularly B/W and almost-to-scale images. Many times you can even use a ruler for measurements if the pic turned out in the wanted scale.
The SA-3 themselves: several parts of 1/72nd aircraft missiles until you are satisfyed; Evergreen and other styrenes for other parts and you are done with it.
Same recipe for the Sa-2 radar, the SNR-125 Fan-Song. Much more complicated than the previous radar, this one has more parts in styrene. Superglue and Hotglue bonds everything in its place. The figure, a kneeled Skytrex 15mm already glued, gives you the size of the thing.