Edit 20/9/17 - Bunnings have dropped their price to $4.94 per kg
https://www.bunnings.com.au/glitz-1kg-green-borax_p4460527
thanks to Daydream
posting this primarily as a parent with a kid who is into making slime.
bought borax at Bunnings on Sunday and it was $9.40 for 1Kg.
here we have an upcoming deal for nearly half that price.
To make slime-
Borax
PVA glue (4litres for $21.69 @ bunnings)
Shaving cream - ~$1.45 @ coles
I should note that the Bunnings PVA is not the best for slime. it doesn't produce as elastic slime. check out Lincraft or BigW for decent PVA.
EDIT- about the Bunnings 4ltr PVA. my daughter was making another batch of slime today using the bunnings PVA. she added some shampoo to it and mixed that together for 5 minutes and then added in the borax and shaving cream and it came out normal
What are you meant to use borax for? - besides making slime.