Ambush Alley Games make rules for modern day combat - aimed primarily at a well equipped modern force against a large force of untrained insurgents or militia - e.g. Iraq, Somalia, Afghanistan. But they also privide rules for combat between modern armies too.
have a look at their store for details. While they don't sell minis as far as I am aware, they have links to companies that do.
http://www.ambushalleygames.com/
Eureka Miniatures (from Australia) sell some interesting and non-mainstream 28mm figures too, such as Australian Special Forces and NATO troops. And they also have overseas stockists.
http://www.eurekamin.com.au