Only purchase a historical OOB.
Use one of the OOB sites, like:
http://www.bayonetstrength.150m.com/index.htm
Purchase:
one infantry battalion
Supported by:
one armoured company/squadron
one light or medium artillery battery (only one FO)
As for captured kit, I only let myself buy a captured 'trophy' vehicle if I actually captured one in a previous battle (it was abandoned/damaged and was behind my lines by the end of the battle). I can only buy the exact model.
Cross