My neighbour bought 2 at Kelebek on the Kas Road, you can also buy them from Osman (the curtain man) on the Kalamar Road and also NEED will order them for you. As you say there are different grades and I can't remember whether the flat plastic strip is better than the round plastic, maybe one of the suppliers can help. Most will offer a discount for a big order so I would haggle. However as Kevincat99 says, they deteriorate fairly quickly if exposed to the sun for any length of time and for that reason we went for the teak sunbeds.