First stop, of course, would be various Infinity figures. The Panoceania Fusiliers might work, since they wear comparatively little armour. The Ariadna Kazaks are in a similar vein, and the Van Zant figure could be modified into a passable Batou or Boma. The main problem, is, though, that you would probably need to "keep in style" once you start with those, and this might be problematic.
Another option would be using the HLBS Ultra-Modern line, maybe SAS Hostage Rescue Teams as a basis. The Seburo carbines would require some converting, though, as would the heads to get some passable likenesses, but you could also check the various types of separate heads now available (Anglian via Empress, SotTR, Pig Iron) if there are suitable bases for conversion available.
Finally, you could go for the Foundry Street Violence range and the Future Warriors available from EM-4, Mirliton and (second gen) Copplestone, although these would require conversions as well. There´s a number of figures in the various SWAT blisters which would be suitable with little work, such as the one big SWAT specialist with M60, who would only need the bionic eyes (and a ponytail if going for the TV series version) to pass as Batou.
When I did
my various GitS stuff, I chose to use more or less generic figures, and to sculpt or convert the more iconic ones. Unfortunately, I only managed to do Batou before I lost interest in that specific variant of Cyberpunk, but I´ll probably return to do some more figures. Although I´m currently more interested in doing some Appleseed stuff now that I got the GZG character figures for that setting.