I did it the other way around a few months ago - lent my brother a set of jump leads, happened to be in ECP picking up an online order the next day and spotted a pair on the shelf priced up at £12.99.
Tempted to gift to my brother, but decided to check the online price, which was £4.99 before discount and £3.37 after their offer code of the day! The guy behind the counter said it took a few mins to come through if I online order, so tried to get close with trade discount - which he couldn't! So I ordered "online" in store, through quidco to get 50p cashback and "collected" three minutes later for a total cost of £2.87 (after cashback which was paid with no issue) I got
these jump leads.
So they certainly have a variable pricing strategy, but that isn't always a bad thing