Where is the best (cheapest) place to buy Amplex Diamond Paste. I am planning to buy the .5 and .25 micron grades, but I am not sure if I should get the 1 or 3 micron as well. I am planning to buy a Norton 4K/8K and Thuringen in the near future, so would any of these grades of paste be redundant or unnecessary? My goal is to get the sharpest and most long lasting edge as possible.