For Aidyn I used only Grobags, and could only afford one in each size.

For Eva I was more prepared, looking around for bargains, and I got a beautiful Dreambag from the UK for less than $25 - the quality was just as good, if not better than a Grobag. Unfortunately DreamBag now have an AU website, so the price of them has doubled since I bought one.

Online I also found a Living Textiles sleeping bag on clearance for $20 - again, wonderful quality!

There are also cheaper makes on Ebay... but the quality and fit is not quite as good, I think the brand is Cozy Touch?

I also picked up a thin stretchy cotton bag from Best & Less for only $10, and this is the one that Eva wears on the cooler summer nights (on the hot nights she doesn't need anything at all anymore!).

Good luck in your search...