I'm currently building my own sub250. I chose to go with:
VTX: DJI O4 with it's pigtail linear antenna
FC and ESC: Speedybee f405 mini stack
MOTORS: 1204 size with 2750kv (kv for mine is on the lower end, you could get any within the 3-4k range)
RX: Any ELRS rx will do
Battery: tattu r-line 850mah.
All of this added up to 245g.