We are almost too late to get rules and stuff
. The rules from D20 are going out of print soon, so if you can find them online or at the local shop, grab them. d20 let the license lapse as the studios wanted more money to renew. Figures can be had of modern troops that are similar, but the special figures are now scrapped by the companies that made them, molds destroyed, etc. 
, or at least, that is what they told the legal departments of the companies. Shame, really. I did find skirmish rules for Stargate online at a Yahoo Stargate Gaming Group. They are listed as fan material and are a free download, so join the group and get the rules and the history of the problems folks are having. There is also a paper model of the stargate in the files section of the group. No instructions, but a decent model. Other companies supposedly still have materials, but they dont advertise it. I got the basic d20 Stargate book for the wife's birthday, and there are still most of the supplements on the shelf, and I see lots of these on Ebay. I havent played the skirmish rules yet, but on first looks, they do look pretty good and thorough. Also lots of materials there on stuff you can use to make up an Egyptian looking area for your games, but I still use Caveworks and other WWG products, and will be adding the Mars set for it as well.