If you have, or are willing to develop even the most basic sewing skills, you can make your own sling. This will save you money, and allow you to choose the fabric, size, and level of padding that suits you best.
NOTE: Many of the tutorials loaded to the web recently suggest sewing your fabric in half or in some other way creating a double layer sling. While this is possible, it will definitely make your sling harder to adjust. If you have the fabric on hand already, and time to experiment, it might be worth a try, but I prefer to save myself the aggravation and choose a fabric of suitable weight and design for a single layer sling.
Sleeping Baby not only has great instructions for sewing the sling, but great suggestions for choosing a fabric as well. With that in mind, please recognize that the links below all have some good ideas, but their inclusion here does not imply my approval of all of their methods or supplies.
Nearly comprehensive sling/carrier sewing list: http://www.thebabywearer.com/lists/Sewing.htm
There are now a number of great instructions online for using rings and a scarf or similar item to make a sling without sewing.
An onbuhimo (or onbu for short) is a Japanese back carrier. It uses a small rectangle, 2 long straps and 2 loops or rings to make a back pack shape for carrying a child. Depending on construction and technique it can be used for babies of many ages, carried on the front or the back of the parent. There is a crafty and simple tutorial at Placemat onbuhimo tutorial
For another example please see Onbuhimo Tutorial
If you have never sewn an asian style carrier before, you might want to check out the sleeping baby crafts page (as listed above and in the second link) or the sewing groups listed below for additional explanation of terms and help with construction details. An onbuhimo is a lightweight, comfortable way to do simple and secure back carry. This is a great second carrier project.
Once you have examined a sling or a sling pattern you will see that with a little experimentation you can have the sling that's ideal for you.
Occasionally we get requests for ideas for places to buy fabric. Here are a few, we look forward to hearing of more as you send them to us.