Budget is usually the primary indicator for which casket or urn to purchase. If budget is not a concern, choosing an urn is based on some form of design that represents a characteristic of the departed, and then considering where the ashes are going to go.
If the purpose of the urn is going to be to bury it, then a biodegradable container is a good option. Biodegradable containers can be filled with other mementos of the departed along with the ashes and safely planted so that they can be absorbed back into the earth in a timely manner. Other caskets may take much too long to decompose.
There are several catalogs available, which a funeral director should be able to supply, that offer a wide variety of quality and prices that can help make urn selection easier. Some people prefer to get one medium-size urn and then several smaller-sized urns and spread out the ashes among family members. However, until the ashes are scattered, the final choice is not necessarily one that needs to be made right away. Many loved ones leave the crematory with the ashes in the plain cardboard box from the crematory and find an urn later on.