Most lines of paint should include a buff in their catalogs. Andrea and Vallejo acrylics do. Andrea's is a little darker, almost like the lighter shades of khaki cloth used today (eg, Dockers)
For my toy soldiers, I use Testor's gloss enamel Cream for the lighter buff shades that you see with some Continental uniforms, and for Prussian and Austrian cuirassiers. I also use it for flesh color, too.
Prost!
Brad