I just bought (online) two pairs of spiderman wellies for £3.50 each.
Other choices are Minions, Batman and Avengers and more although the prices go up slightly on some for bigger sizes. IMPORTANT : sort list by price low to high because some of these appear further down but are more expensive for some reason.
Girls ones there too Disney Princess, Frozen, Minnie etc but these start at £4.99.
I rang my local store who said the deals online are different to in store so you can click and collect - £4.99. Yes - this is the most annoying thing about Sports Direct!!!
It still worked out cheaper for me because bought a few items and wellies are nowhere near this cheap elswhere especially these ones!
You get a £5 voucher back when you collect or pay same price for delivery.
I also bought Kangol school shoes reduced to £5.50! check them out too.
Theres also girls light up character sandals going for £10.50
Sorry if theres no pic, Hukd app is really playing up at the moment for me, its driving me nuts!