Buying your own coffee grinder, therefore, can be a fantastic investment: you have full control over the grinding process, and have the distinct advantage that you can grind the beans yourself just before they are to be brewed (this is recommended in order to achieve the best cup of coffee possible. If beans are ground more than a couple of minutes immediately before brewing, they can become stale and the flavor will be impaired).
When you buy a coffee grinder online, make sure that you do enough research to understand what you are buying. The range of grinders offered by different web sites can vary immensely from company to company, and of course the price will fluctuate too. The two main varieties of coffee grinder are burr grinders and blade grinders: burr grinders grind the coffee using a mill-like action, and tend to grind very evenly and cleanly, whilst blade grinders actually chop the bean into pieces at a much faster speed than burr grinders, resulting in coffee grinds of varying evenness, and producing a dust that can clog up espresso machines.
Whichever machine you opt for, ensure you choose a web site that allows you to shop securely, and make sure you take into account the shipping charge when making your purchase. It can also be useful to buy a machine that offers a warranty, just in case anything goes wrong.