Halo Sleepsack?

Does anyone have experience with these? If so,how about the sizing? I'm considering buying one, but I don't know whether to go with small or medium for a newborn. They look pretty large to begin with.

[Momof3Labs]

I'm not familiar with these specifically, but they seem awfully expensive for what they are. I went to the Carter's outlet near us (there is one in most outlet malls) and found almost identical sacs (except these have sleeves - which can be cut off if you want) for about $8 each. And they fit up to about 20 pounds.

Lori
due 10/12 w/ #1

I bought the small for my newborn. I think the weight range is 10-18 lbs. He is now 11 lbs. They do seem really long. And they are a bit pricey. I'll have to check out Carter's. Does anyone know what fabrics are used?