as a collective you may not get a posistive income for some time
if you look in the manual, under "alien races" you can see the collectives modifiers, and they make money through plundering planets, and are pretty good at producing food
though keep in mind your housing can be filled 2X its maximum as a collective(this is all in the manual)
so what you do is, sell food, and attack people and plunder some colonies, but your per turn income may still remain negative.