Just warning you that those are Asian sized ponchos and that is the as-cut size, they are smaller when sewn up [ I have one but in the winter camouflage] so while they work as a poncho they are small when used as a tarp.
Kids needing shelter were why I bought my first Megamid, speed of erection and sheltered space for the kilo carried being the main reasons, but being able to put up the tipi while the kids were sat in one spot was also a factor. Having been a solo parent myself at one stage i know how tight money can be but I had to balance my love of skiing against the kids comfort and safety. I never had to use it in an emergency but it was used many times as a rest and relax spot out of the wind to drink Milo in and eat TeddyBears at Lake Mountain.
Sun shade and shelter from the wind may mean 2 totally different styles of shelter but for shade in summer an Op-Shop bedsheet works very well. Winter with cold wind and rain is different. I also say don't skimp here, but thinking outside the LW/UL side of things a cheap pup=tent from K-Mart can be easily modified to give a cheap emergency shelter and those are about $50-
you cut out the PE flooring and they become a lot lighter
http://www.kmart.com.au/product/3-perso ... nt/1936828Or the almost useless as a tent wedge that still offers shelter from the wind
http://www.kmart.com.au/product/2-perso ... nt/1679803Naturally such tents need to be used with care and do need modifications such as side guy points but for emergency use I would be OK doing that, and replace the cheap steel pegs with alloy to save weight when funds allow using trekking poles in the mean time rather than the crapola that they are sold with
I'm looking at these as emergency shelters not as tents. Sometimes you find these in Op-Shops for $5 or $10-