I've noticed that collections more often than not do not represent good value to Yoto Club members.
For example - The Rainbow Fairies Collection Daisy Meadows requires 7 credits, and costs £24.99 - using 7 credits is the equivalent of £35.
Other collections where the card quantity exceed the value, also fall into this poor value. I think it's just a blanket 1 card is 1 credit - but collections don't always work with this formula.