Good price for kiln dried sand

[K in Kent]

I usually get my KDS from Wickes out of convenience and habit. I was checking stock levels in my local store to collect some in the morning when I noticed a Google Ad for Travis Perkins where the same product is nearly half the price - £3.92 at TP compared to £7.30 at Wickes.
Both for 20kg bags by Tarmac.