We have been wanting to do the exact same thing (just making of the simple cotton bags w/drawstrings that is). Since we sold our sewing machine as it was never used, we would have to borrow one. Otherwise, if the bags were reasonably priced, we would most definitely buy them. I guess it all depends on the size and material for how much we would pay.

I would buy them. Most store-bought or handmade bags just aren't the right size.

However, I would want them padded in most cases rather than unpadded as you say.