does it have to be one for you to sew? 
iv got this and its fantastic! 
http://www.amazon.co.uk/Moby-Wrap-Almon ... 018&sr=8-1
there are other makes that are cheaper or its possible to make one yourself. 
its just one long piece of fabric. no need to sew anything, all you do is cut the fabric to size and thats it! 
link to video instructions how to make baby wrap:
http://www.youtube.com/watch?v=15Aj1IFtlyo&feature=fvsr
instructions how to use your wrap:
http://www.youtube.com/watch?NR=1&featu ... hBmqw7npYU
iv had a few different baby carriers when i had my fist child and i gave up useing each one as they hurt my sholders and back, i couldnt breastfeed in them and my daughter didnt settle in them.
it was recomened i try a baby wrap or a sling and after looking on amazon and reading all the reviews i bought the moby wrap as it was the best seller 5 star rating, and i looked up separate reviews online when were all positive. 
since iv had mine it has been excellent. its so comfertable, the weight is spread eavenly over my sholders and back, nothing digs in, its soft streachy t-shirt fabric which sits snugly against me without any buckles or sticky out bits, its just like wearing a piece of clothing.
there are multiple positions to put the baby in, for breastfeeding, facing out on in, on your back, front or side, for tiny babys and for older toddlers. 
it can be used up to the child is 3 year old. 
its fantastic for settling the baby. whenever hes colicy, teething or just crying i pop him into the breastfeeding position and go for a walk arround the house, within 5 min hes fast asleep wether he has fed or not. he likes being all snug and secure and he allwasy settles down quickly once inside. 
i can carry my 6 month old in the wrap whilst out shopping or wherever without it hurting my back. in fact, it actually helps support my back, as the weight is evenly spread out over your entire back and sholders, it feels good wearing it.  
honestly its the best piece of baby 'equipment' iv ever owned! wish id known about it when i had my first child!