I get my gro bags from eBay (British seller ... Can't remember the name off hand). I got a two pack for about $50 including postage. They r the genuine gro bag and they are great.
My dd has 2.5 tog for day or warmer nights and she has 3. Tog (only available in uk) for cold nights. I live them and can't recommend them enough. Have a search on eBay and you'll see some great deals!!!