Crusade asks you to build a 50 PL Order of Battle, which is going to be roughly 1,000 Points for most factions, but you don’t have to play missions with the full roster. Combat Patrol missions, for example, only use 25 PL’s worth of units drawn from your Order of Battle.
So you could take the same collection of models, say a five-man Intercessor Squad, and list them on your Order of Battle twice just giving them different names and tracking their XP separately. You’ll just never be able to use both in the same game... at least, not until you buy some more toy soldiers!
Incidentally, the various Start Collecting boxes all tend to average around 20 Power Level...