I would also check some home improvement outlets like Lowes or Home Depot. I believe they have kits that can curve the corners with prefab moulded panels that can be painted or plastered over, for those trying to elimate corners in the house for aesthetic purpose, but would work for what your trying to do as well. As Steve said, doing it yourself would be alot of savings and these kits I think would be cheaper at one of the home improvement outlet stores.