Yes a lot of it online is borax substitute for domestic use.

If you just need a small amount, you can scrape a borax cone with a knife.

For a 100 g of powder go to https://atthebench.store/product/bor...x-powder-100g/

Cousins sell a kilo tub cheaply:https://www.cousinsuk.com/product/flux-powder-borax. Dennis