Have been invited to join friends at an extremely expensive event. They have a spare ticket - their treat. Normally I would offer to pay my way, but frankly that isn't really an option. It really is very expensive (think Centre Court for the mens finals, but it's not that!)
Would you: - Gracefully accept and concentrate on being a lovely guest. - Make some sort of contribution towards the cost. - Take a gift ....... and if so, what? - Something else?
They obviously like you and enjoy your company. Take this offer at face value. Accept graciously and be a great companion. You could treat them to refreshments whilst you're there and You'll be able to treat them to something down the line ( it doesn't have to be the same £££ - just the same goodwill)