I just had a look on eBay -here's one venom 300 in your budget. It packs quite small and weighs less than a kilo iirc - but check Vango's site for specs. This one might be last year's model but that isn't very important I hope.
It has baffles in the right place. The hood closes easily to just a breathing hole if need be.I've got one and use it mostly with a basic Decathon rollmat. Sometimes with a Vango Trek self inflating mat. Sometimes with both! You'll know that what you put under the bag contributes a lot to how warm you will sleep. Just wearing clothes inside the bag won't help without insulation from the ground.
And while I'm teaching you how to suck eggs ... Choose the zip on side you sleep on. Then when you get too warm and unzip the bag drapes over your upper shoulder like a duvet. You will find yourself laying on the zip pull occasionally, however that's offset by the alternative of a cold torso.
Other bags are available. Vango pitch their products firmly in the DoE / affordable range and serve that market well. The Alpkit bags are also good value and able to cope with more extreme cold than the Venom range - they also cost a bit more. The lasses like them because they are very warm and girls tend to need that. The Skye 600 is a good useable bag.
Wish your daughter luck for her gold - my son does his this year.
Edited: 29/06/2012 at 11:56