GG offer a £6 goody bag, but it isn't possible to buy a £6 voucher. That's daft.
If a £6 voucher was available, it would be a unique selling point in the market and very attractive to old coots like me who have been frog-marched into buying a smart/mobile phone by their kids as a senior form of safety reins.
Unlike modern yoof, I don't wander around gazing at a piece of glass, oblivious to my surroundings, but it'd be nice to know the device in my coat pocket would work if needed - and at minimum cost.
I guess similar arguments might apply to smaller children.