I suspect the stock will depend on what your local Waitrose will sell, but plenty of E-cloth stuff in mind, with i.e. washing up sponge for £1.50, window cloth for £2.50 etc. All marked half price on what are pretty average going prices (some spring cleaning event on atm)
Only need water and can be washed up to several hundred times.http://www.e-cloth.com/
As recommended by Miele, Siemen, Good Housekeeping Institute and more.
Ps. I love my stainless steel one!