Past deals have mentioned calling HP to request corporate rates for big discounts through their sales call centre. I needed a replacement laptop, so tried this approach with some luck, but then stumbled on a URL redirect which lets anyone access the corporate pricing.
This shows a variable discount on most items (not all). My laptop (Spectre X360 i7 16GB 1TB AP-130110TU with 3yr accident protection) was $4,398 ($3,799 + $599) and I got it for $2,777.26 ($2,422.77 + $354.99). Shopback was offering 7% cashback at the time (currently 6%) so in my case with $194.41 back total cost was $2,582.82; a saving of $1,815.15. Also offers discounts on accessories, and delivery is free with HP Online.
I tried retailers like JB HiFi, Harvey Norman, etc for similar spec machines and all said there was no way they could get near to matching the online price. Of course your experience may differ, and you might not need such a high spec machine, but it's worth checking out if you're shopping for a new HP. While this could be cancelled at any time (unlikely as I found it in a printed promo), and cashback might not be honoured in future, go for it while you can. Only warning is that HP logistics is a bit of a shambles so expect confusion and delays. Hope it helps
Update: orders through this link work with any email address. No corporate email required