Second hand 三摺床玉 bought from Pricerite. Grey color and use not more than 8 times. It's at my Kwun Tong office now.
<SOHO 三摺梳化床,灰色,910WX600/1800DX560HMM,SW-9B>
I see one store (in Sai Wan Ho) which mainly sell the traditional wedding items but do have foldable 三摺床玉, range from $200 to approx.$400. You may want to check it out too.