Diesel: 330-400 CFA/litre (more expensive inland), Petrol slightly more expensive.
Hotels: 16,000 CFA/night is cheapest decent place in Libreville (Hotel Tropicana, book a few days in advance), in other towns 5,000 - 10,000 CFA is standard for a double room with a fan, 12-17,000 for air con/tv. If you stay in a village, either with the Chief or camping, its best to contribute 5000 CFA per night and buy him a
Food in 'cafeterias' is about 3 x the price of Cameroon but still cheap - 1,000 CFA for omlette, coffee and bread, 1,000-1,500 CFA for a big plate of meat/fish and rice/manioc/bannanas. Fresh grilled fish is excellent, especially in Libreville and Lambaréné, 1,500 - 2,500 CFA for a big fish and fried bananas. 'Western-style' food in a restaurant starts at 5,000 per plate, only in the bigger towns.
Beer: 400 CFA /bottle (640ml) in big towns, 500 CFA in small towns.
Prices as of August 2005. 1,000 CFA is approximately 1 Pound or 2 dollars.
If you do go, don't just do what the others do and go to Libreville - see the cool places like Mayumba, Lambaréné, Ikobey, Plateau Batéké etc. Gabon just created 13 National Parks, so plenty to do.