Where can I find a lightweight summery sleeping bag for a 14 month old?!

I know there are grobags around but they are just too expensive, even buying of e-bay they go for a high price.

Last summer I had no trouble but this year I have looked in most big name stores and they either have nothing or have them in very small sizes.

My DD still needs one as she never leaves a sheet or blanket on and the bags she is in now are just getting too warm.

TIA.