Question: how much cost v bucks?
Answer: Fortnite - 1,000 V-Bucks. £7.99.
Fortnite - 2,500 (+300 Bonus) V-Bucks. £19.99.
Fortnite - 4,000 (+1,000 Bonus) V-Bucks. £31.99. Buy 4,000 Fortnite (+1,000 Bonus!) ... 
Fortnite - 10,000 (+3,500 Bonus) V-Bucks. £79.99. Buy 10,000 Fortnite (+3,500 Bonus!)