hotels been found near the island venice, one is milano, 25 km away, and the other is mogliano veneto, about 17 km away, cost per person/night 23-24€ ink. breakfast. we can live there and drive in. the hotels in the island, i think we can forget, as we see the prices.
so the fixed costs (traffic and hotels) make up to around 100€/person if we got 5 persons (from Graz to Venice)