[quote=ulsterwarrior]
So it costs 5 Bullis for every one man, right?
[/quote]

Every season you pay 1 Bullis to a Soldier for payment for being a soldier.
The "5/1" being talked about is equipment, which is something totally different.

Plate armor costs 20/3. To "Unlock" or "Purchase" ONE set of Plate Armor, you MUST pay 20 Bullis. After that, you only need to pay Upkeep cost to keep it functional and strong. You pay 3 Bullis per season for Upkeep. There are 4 seasons in a year, so you need to be able to pay 3x4 per year. In the end, a single Plate armor costs 12 Bullis per year for Upkeep.