I agree online is cheaper, but these 'groups' are a terrible terrible buy. More often than not out of say... 5 groups you end up with 2 that are non aquatics and one that is high light so 3 groups die and you're left with something cheap and common like cabomba and water wisteria or similar. So you end up paying say £6 for £2 worth of plants. A definite false economy.
I suggest wandering over into the planted section and asking for some ideas of plants to use in your tank. Also there is a pinned topic in the planted section with reviews of plant selling websites.