Hotel rooms in Sicily run $200-400 per night per couple in high season. Six people in a villa with a private pool, a full kitchen, and a terrace with sea views run $580-700 per night for the whole property. Split six ways, that's under $120 per person.
The Thinking Traveller specializes in exactly this. Their Sicily villas are vetted, the descriptions are accurate, and they have local staff on the ground. Browse their Sicily collection and filter by guest count to find what fits your group.
WHY SICILY WORKS FOR GROUPS
Sicily has the food, the history, the coastline, and the weather from May through October. It's also significantly cheaper than Tuscany or the Amalfi Coast. Local restaurants run $20-35/person for a full dinner with wine. Palermo, Taormina, and the Valley of the Temples are all worth a day each. The island runs on a slower clock and that's the whole point of going.
THE FLIGHT
New York to Palermo (PMO) or Catania (CTA) runs from $284 one-way in September. Search and set a price alert on Skyscanner to catch the dips.
THE NUMBERS (7 nights, 6 people)
Villa rental 7 nights at ~$640/night: $4,480. Flights 6x NYC-Sicily round trip at ~$568/person: $3,408. Car rental 2 cars x 7 days: $700. Food and wine: $1,400. Activities and entrance fees: $500.
Total: ~$10,488 for 6 people. Per person: ~$1,748. Per person per day: ~$250.