Both my kids are wheat and dairy free (not gluten free, although often it is easier to use the gluten free products). DS is also soy intolerant, but we only exclude major sources like milk/yoghurt. He seems to be fine with soy IN products, including in home baking, and with nuttelex, so that intolerance is obviously much milder than the other two. I find normal recipes with the flour/butter/milk substitutes work best for us.
Here are some specific products from our cupboards right now....
Rice crackers - plain we eat with salsa, otherwise thai lime and coriander. I think tomato and balsamic is also ok, but kids find it a bit hot due to the balsamic
Ogran outback animal biscuits
Ogran Itsy Bitsy bears biscuits
Leda Choculence (like tim tams)
Ogran corn crispbread
Eskal Deli Crackers
Sweet William dairy free chocolate
Aribars (like LCM bars)
Freedom foods muesli bars
Kidscare rice rounds
Cool pack popped corn (10 pack)-
IGA gluten free pizza base mix
GF SR flour and plain flour
Rice cakes
Freedom foods pancake mix
Melindas choc fudge brownie packet mix
Deliciously free mud cake mix
Ogran easy bake bread mix
Well and good cookie mix
Well and good muffin mix
Taco kits (only the proper tacos, not the soft ones)
Patties (frozen section coles) - lamingtons, sausage rolls, veggie sausage rolls, bread, fish bites, crumbed fish fillets, chicken nuggets. This bread is the only gluten free one I have found that is also dairy free.
Go natural popcorn fruit bars
Minties/gummy bears/allens lollypops - all made with corn syrup instead of glucose, although a coeliac friend I have recently told me that wheat glucose is sufficiently removed from being wheat as to not have gluten in it (ie sooooo processed).
If you are working on it being intolerance, might I ask why gluten free rather than wheat free? Wheat is a more common intolerance than gluten (the top ones being wheat, dairy, soy, eggs, fish/seafood). Generally gluten is the culprit when coeliac is involved (dd has been tested via endoscopy, DS will be tested later this year). Because of this, they eat cornflakes and rice bubbles for breakfast. But for snacks (they don't like them with milk) they also have cocoa bombs and honey rings (from gluten free section).
For all of the above products, I have to shop at IGA, woolworths AND coles - frustrating but well worth it. IGA also has some popcorn, in family size chip bags, there is blue and green bags, the green backs are absolutely delicious - but I cannot remember the brand and we are out of these.
HTH