Yeah, I'm on a kick.
The SJGames website is somewhat...difficult.. to navigate when wanting to find particular things. I was asked about OGRE expansions and they are all over the place. So here is a list of some of them.
The OGRE Designer's Edition (ODE) was on Kickstarter and included EVERYTHING plus some. It is out of print but can be found regularly on Ebay.
Do not fret though. OGRE 6th Edition in the same scale is available. This is the core game. The original nuke blasted map and the original pieces.
More pieces and OGRE's are available in the just released OGRE Reinforcements set along w/ rules, terrain, and scenarios.
Much of what was in ODE can be pieced together. The G1,2, and S1,2 maps are available here. The rule book is here. 'Retail Edition' counters of ODE are here.
The '4.5k' Sponsored Counters from the Kickstarter (like the fantastic Nihon:North American Divisions set) are available through here. I believe some of them are sold out though.
Other KS exclusives can be found from time to time at outrageous prices on Ebay.
The recent plastic minis Kickstarter units can be pre-ordered here.
Hope this helps.