Well, here is a basic list for 500 that does only a little, but still can win games...
It's Battle forged so you get the special rules (re-roll Warlord Trait, Objective Secured for Troops)
Winged Dakka'rant: Wings, Twin Brain Leeches, Thorax hive: Electro grubs...240
Warrior Brood, x3, Strangle Cannon... 100
Termagant Brood, x20 80
Termagant Brood, x20... 80
That's 500 even with three Objective Secured Troops, some decent shooting, and a Winged Tyrant.
Once you start adding take a good look at adding Carnafexen (Brain Leeches) and Mawlocs. Both do very well against a wide range of foes.
I personally like Tyranofex, with Acid Spray, and a Thorax hive, in low point games it is almost unkillable.
In any case, good luck! And welcome to the Hive Mind!