usual first turn purchases:
Russia w/ 24 ipcs - 8 inf
Germany w/ 32 ipcs - 9 inf, 1 arm
UK w/ 30 ipcs - usually a combination of AC and a transport, however may purcahse air or industrial complex.
Japan w/ 25 ipcs- 2 transports, 3 inf
US - w/ 36 ipcs - combo of trns and inf.
Round 2:
Japan, Russia, Germany - all inf, UK and US - inf and transports
Round 3: somewhat the same,
Round 4: some agressors may go a little crazy and buy more armor.
note: these are not hard and fast rules by any means. A lot of time purchases might include surprises such as IC’s, ftrs, bombers, subs, and rarely battleships. Armor, although quite useful at some points, are not a good standard unit for many reasons, including but not limited to those mentioned previously.