Last year the workshop tickets cost £5. A lot of the sessions in pubs are free. Concerts between £7 & £10 I think. An evening dancing in the Pavilion between £9 & £16 (£14 typical for an early + late ceilidh).
Paying separately means you can't be spontaneous, drop into a concert with friends, then wander somewhere else for a bit.
A full week's ticket gives excellent value.