You should ask yourself...
How will the urn be used? Will you keep it inside on the mantel, bury in the ground or a wall niche or scatter as your loved one wishes?
What are the best materials for an urn? A ceramic, stone, marble or metal urn is not biodegradable as wood urns are and are considered a permanent cremation urn. Wood ones are too if kept inside. If they are buried in the ground they will biodegrade and are considered a non-permanent urn.
What is an appropriate design for an urn? There are no rules! Your urn is a personal item you choose for yourself or your loved one and is meant to reflect them or if for you, to reflect what brought you joy in life. The variety is almost limitless.
How much should I pay for an urn? Buy within your budget. There are many urns on the market that are very reasonable. Do your research.