Most garden tools used for digging in gardens almost always have a garden spade and fork to enable you to move larger quantities of soil. This is better than a trowel which is much smaller and would take a lot longer. Spades are in a gardeners tool box much like a rake or clippers and are mainly made from stainless steel and area available from most of the major manufacturers like wilkinson sword who have a reputation for quality steel and draper and spear and jackson.
The most popular garden spades are made from stainless steel simply because they are more robust
in nature and of course won't rust over time. Most have a solid long handle but the wood that is
used varies from spade to spade where at the cheaper end of the market the shaft is made from
polypropylene and the more expensive from hardwood.
Most spades can be easily purchased for less than £20 so it's not going to break the bank. Some models incorporate an additional "foot rest" just above the steel head so it's easy to push down when digging which means less slippage in the wet which can sometimes cause nasty injuries and makes the job of moving soil much longer.
Probably the best garden spade to buy is manufactured with a stainless steel head and a hardwood shaft and is from a well known manufacturer. Some having slightly tilting heads with ergonomic handles for a more comfortable digging experience. Even the most expensive spades are less than £30 so really it's best if you pop down your local garden centre or diy shop and have a look at what is on offer and choose one that you like the look of.
Almost all spades can be bought online from many stores but just watch out for delivery charges because a spade is reasonably heavy and quite bulky (and this is how delivery companies charge for carriage so you might just as well go to your garden centre and have a look around first).
Perhaps also consider buying a garden fork at the same time as the design will be the same as your spade and the usage of both will be similar so you are not going from one type to another when digging and landscaping your garden.
Professional spades cost just a little more at perhaps £40 to £50 where the head is made from carbon steel and rivetted for additional strength in the shaft. They also have additional coatings to help protect from the weather and soil. Most handles you can grab with your hands but some have "T" handles so you can push harder into the earth. Others have light weight shafts so the spade is simply lighter to handle and others are longer for taller people to use without having to bend their backs.
Like any garden tools your spade should be washed in soapy water after use and dried and stored when not in use. Stainless steel should not rust if looked after properly and even carbon steel spades are treated so should not rust either. It's best not to leave spades outside in the rain as the shaft could start to deteriorate and rot over time and although this tool is not very expensive when compare with some power tools it's a cost that can be avoided.