Mark has been a good friend of mine for over 20 years. He is a good local surfer and has kited for a few years. He has been hosting surfers and windsurfers since 1989.
He has a lot of choices on the South Coast at Silver Sands. Some of his apartments are in the $50-$60 range per night and have full kitchens and will sleep 2-6 people. They are all located in nice areas and some are oceanfront. Bring some friends and split the rent!
Barbados can be as expensive as you want to make it but I do not think you can do it much cheaper than with Mark.
Another good choice is Zed at www.surferspointbarbados.com
Zed is another great guy and a very good surfer. He even beat Kelly Slater in a few contests when they were juniors.