If I want to buy a kids sleeping bag, how much will it cost?

You would think that it's a simple task buying a sleeping bag, but there are many factors to consider before making a decision.
Firstly you have to figure out why you are buying your sleeping bag: Is it to have for sleepovers in your house, is it for the kids, is it for camping trips or serious hiking outings? All these questions will affect how much you should spend and the weight and quality of sleeping bag that you buy.
Different Shapes
There are 3 basic sleeping bag shapes:
Traditional mummy style which has tapered ends and traps the heat well.
Rectangular style which are bulkier and less heat efficient but they can be unzipped, so not only can they be used as a blanket but also give more space to move around in.
Semi-rectangular style which is quite a good compromise between the 2 options above.
Choosing a Fill Material
There are 2 main types of fill material for sleeping bags; Synthetic or Down. Here are the pros and cons of both types.
Synthetic: These sleeping bags weigh a lot more than down filled bags and are bulkier but they cope much better with being wet as they retain their insulation well. They also dry quickly once wet and have better anti-allergic qualities. Finally, they usually cost a lot less, so if you are camping on a budget - this might be the filling for you.
Down: These bags are made from the fluffy undercoating of geese and ducks. It's a natural material as opposed to a synthetic one and it's really good at keeping you insulated and warm, so it's a good option if you are camping in cold weather locations. The quality varies depending on the bird the down comes from and there are measurements that tell you the quantity of down used in each sleeping bag. These bags are really compact and light but if they get wet they take forever to dry.
What else? Other things to consider when buying a sleeping bag are; Whether to get a lining with it which helps avoid the need to wash your sleeping bag too often. Also a sleeping bag mat which goes under the sleeping bag and rolls up very compactly can make all the difference to your sleep. Read the washing instructions to make sure you can put it in the machine or dryer. Enjoy your sleeping bag.