There are some sneaker freak and Adidas t shirts on footlocker web site that has been reduced to £4.99 each. However if you buy 2 you get £10 off. Effectively making them free. But there is a £5 delivery charge for orders under £60. You can add as many t shirts you want to your order and the total will be £5 when you go to checkout. There are a few different styles of t shirts. Maybe they will honour it maybe not. Good luck
This deal seems to be working with other brand t shirts that have been reduced to £4.99. See a few examples in first comment.