Enlightened Equipment do a Junior Revelation quilt - in both synthetic fill which they call their Apex Junior
https://enlightenedequipment.com/revela ... ex-junior/ or in a down version which is here:
https://enlightenedequipment.com/revelation-junior/I'd probably go for the 20F version (equivalent to -6 degrees C) as it's really lower limit rather than comfort limit.
Revelation Junior is 434 grams in a 20F / -6 degree version and $338.
Revelation Apex (synthetic) Junior is 688 grams in a 20F / -6 degree version and $249.
If you want it to last your 8 year old even longer, you could go with an adult quilt but in a short length which is also an option. (Their X-Short is designed for people up to 5 feet.)
The local Australian quilt makers on the forum may also be able to do a custom quilt in shorter length.
The idea behind quilts being they do away with the underneath which in anycase with down is compressed underneath a person and so offers no real insulation value anyway.
They do though require a well-insulated sleeping pad mat to be effective. Ideally a mat where the R value meets or exceeds the rating of the quilt.
There are also much cheaper kids bags which go down to low temperatures but are a lot heavier and bulkier. (Roman Junior kids 0 degrees
https://www.wildearth.com.au/buy/roman- ... ue/rom1001, Black Wolf Star 500 Kids 1 degree comfort & -6 degree limit
https://www.snowys.com.au/star-500-kids-sleeping-bag , Coleman Youth C3 which is -3 comfort
https://www.snowys.com.au/youth-sleeping-bag ) which are all around $55 - $65 budget but heavy at 1.4 - 1.7 kg range.
So depends what your priority is - lightweight compressible down but expensive, or inexpensive but bulky and heavy.
A quick look at their Warehouse shows that Enlightened Equipment do have a couple of the Junior Apex 20 F in stock here:
https://enlightenedequipment.com/revela ... -charcoal/and
https://enlightenedequipment.com/revela ... rple-camo/That would mean instead of having to wait for weeks to 1 month + depending on their backlog, you could have one of those options shipped straight away.
Best,
Emma