If you can't visit Manufactum's new store in Cologne, Germany, it's worth the extra trouble (and shipping expense) to source these utilitarian retro toilet roll holders. The prices are reasonable; especially compared with high-end Samuel Heath or Waterworks fixtures.
Below: Enamelled cast iron Toilet Roll Holder; from a German ironworks that has been producing bath fittings since 1870; £13.50.
Below: Spare Roll Holder, from the same German ironworks; £13.
Toilet Roll Holder with Cover; from the same German ironworks as the above products; £42.Below: Enamelled cast iron
Below: Manufactum's own German-made China Toilet Roll Holder; £15.80.