I would like to buy a whetstone for knife sharpening but the two stores I've asked at so far had it priced at over $100.00. Is there anywhere I might find a whetstone at a more reasonable price? I'm looking for something fairly straightforward with a rougher surface on one side and a slightly finer surface on the other. Downtown preferably as I don't own a car but can take the TTC anywhere if necessary. TIA.