I have found Hyper Drive's price beat useful in the past.
However, I have just tried to price beat with an item that is on sale at Supercheap Auto and they have declined, pointing me to this section in their T&Cs:
"Exclusions:
The Price Beat Guarantee does not apply where the competitor's price is:
Part of a special offer, clearance, or limited-time promotion."
In the past they have beaten sales items, maybe those staff were more lenient or maybe they have updated their T&Cs?
My response to refusal to price-beat is usually something like, 'Okay - so you'd recommend that I purchase from XYZ instead?'
Most of the time, they just mutter something affirmative, and that's that, but occasionally they pause, and either choose to price-beat there and then, or ask me to hold while they 'escalate' to their boss, which more often than not gets me the discount.
No harm in giving them one last chance, even if it only works maybe 20% of the time!
If they offer to price-match, I usually decline, unless there is some other factor at play (such as significant convenience for me) - I don't believe in rewarding price-matching, as it encourages the business to price higher, and hope to get the sale on a match if that doesn't work.