I am putting down a patio for my in laws and have shopped around A LOT. After going to several builders merchants and negotiating discounts for bulk buying, the best price I got was £1.55/slab. That was for the 16" or 400mm paving slabs.
Anyway, I noticed the B&Q 15% so nipped up with a Diamond card owner, they were selling the slabs by the pallet (of 52) at £62.84- £1.21 a slab. So taking the 10% Diamond card discount off this price they work out at £1.08 each, 30% cheaper than the best price I got anywhere else. Individual slabs were £1.33 after the 10%.
Don't think you can order by the pallet online.