The package does not include the train Zurich to Brunnen, so you can book your own with your Half-Fare Card and benefit from the ~50% Halbtax discount. The Riemenstalden to Lidernen cable car is also pax-purchase at the gate (~CHF 14 with Halbtax) — no advance booking is possible at this small operator, the group simply boards together on arrival.

Saturday lunch on the ascent and Sunday lunch at the Urnersee are also at your own expense, giving you the freedom to choose what you fancy. The hut serves drinks (beer, wine, soft drinks) on a cash-only basis. A sleeping bag liner is mandatory in all SAC huts and you'll need to bring your own (or buy one for around CHF 25 on Galaxus before the trip).

Switzerland is on the higher end for travel costs, but with a Half-Fare Card the train and cable car are very reasonable. Here's an estimate of common extras:

Train Zurich to Brunnen return (with Halbtax): ~CHF 40

Riemenstalden ↔ Lidernen cable car return (with Halbtax): ~CHF 14

Saturday lunch at Lidernen station kiosk: CHF 20-25

Sunday lunch at the Urnersee or Lauerzersee: CHF 25-35

Drinks at the hut (cash only, beer 0.5L): ~CHF 5-7

Sleeping bag liner (mandatory, one-time purchase): ~CHF 25