Hmm...I'll take a stab at this one. It won't be the most powerful kingdom around, but it will probably serve as a decent benchmark.The Army of the Grand Alliance
Fluff: An alliance of dwarves, elves, and humans, the Grand Alliance as a single army works to protect their three kingdoms. Surrounded by powerful necromancers and conjurers (Hey, at ECL 6 you know there'll be necromancer-kings!), the Alliance works to maintain the power of "good" in the world. They disdain other races (even half-orcs and half-elves!), and do not recruit monstrous races or the undead into their forces.
Tactics: The Army of the Alliance is a ponderous, slow-moving force - but few opponents can survive the onslaught once its dwarves reach the enemy. The dwarven infantry forms the core of the force, while human cavalry works as support for the dwarven forces, riding swiftly to wherever their allies need the most aid with crusaders, bards, marshals, and clerics. The elves provide the least to the forces in numbers, but make up for that in magical support, which is typically used for divinations and Dispel Magic and similar reactive spells rather than proactive spells such as Fog Cloud.
Gold spent: The Army of the Alliance spends most of its gold on fortifications and siege equipment, and on maintaining the treasure hordes of a small cadre of silver and gold dragons that work with the Army.
1 ECL 6 character with 8 bonus feats. Lord Jhoram, Human Cleric 6 of Pelor
2 ECL 6 characters with 4 bonus feats. Thane Beardstone and Arcanist Pallast, Dwarf Cleric 6 and Elf Abjurer 6 respectively.
4 ECL 6 characters with no bonus feats. (1 NPC-class one.) Let's grab a human warlock for scouting, a pair of human druids for battlefield control, and a human expert as a spymaster/skills guy.
10 ECL 5 characters. (4 NPC-class ones.) Let's grab 6 elven abjurers and 4 elven adepts.
18 ECL 4 characters. (8 NPC-class ones.) 10 human cleric heavy cavalry, 8 elven adepts
60 ECl 3 characters. (30 NPC-class ones.) 30 human cleric heavy cavalry, 30 elven warriors (archers)
350 ECL 2 characters. (200 non-commmoner NPC-class ones. 50 commoner/NPC class multiclasses. 50 pure commoners.) 20 human crusader heavy cavalry, 20 human marshal heavy cavalry, 10 human bard light cavalry, 200 dwarven warrior heavy infantry, 50 expert/commoner elven scouts, 50 human commoner siege engineers
4000 ECL 1 characters. (1000 non-commoner NPC-class ones. 2750 commoners.) 250 human crusader light cavalry, 1000 dwarven warrior heavy infantry, 2750 human commoner conscripts
There's a basic army, anyhow