Just come back from there, if you buy water and basic food etc its about the same price maybe a bit cheaper. As for restaurants barbados probably has the biggest selection of top quality restaurants in the carribean (The Cliff and Reataurant at Southsea are the best). So obviously these are very pricey. but if you go to the local basian restaurants then its very good value, oistins for instance is a street full of local fish and meat stalls, fish will cost you about 50p. If you go to clubs out there, you normally pay an entrance fee and drinks are free, normally costs you about 20pound to get in.
You can get riped of with jet ski hire, so be careful, some could try and charge you as much as 100 Basian dollars (about 34pound) just for half an hour, you should try and get hire for 70-75 basian.
also highly recomend hireing a mini moke, its a little car, then have a drive round the island...great fun