I'd second paintball masks for the kids because they're easier and potentially cheaper than comparable two-piece solutions.
I just started in December, here's my list of items I have acquired (has overlaps with ThunderCactus's):
- Rifle
- Charger (Bought a Turnigy Accucel 6)
- Batteries (I got 7.2v Turnigy lipos)
- Goggles (purchased mil-spec Revisions)
- Mesh Lower Mask
- Gloves
- Rifle Sling
- Speed Loader
- Extra Mid-Cap Mags
- Boots
- Barrel Sleeve (depends on where you're playing)
- Ammo (0.25 was recommended to me)
- 1982 Canadian army surplus gear (C7 pouches + belt), holds my m4 mags
Nice to have but still working on:
- Plate Carrier
- Knee Pad (you can get away with one)
- Radio (Looking at Baofeng UV-5R and UV8-82)
- PTT (Kenwood Style adapter)
- Radio Headset
- Gun Bag/Case (Was recommended to check Canadian Tire for Hard Cases)
- Red Dot Sight (can be hard to get down on your iron sights with a mask on)