This is a very useful video on how to create a lightweight shelter from a standard 10’ x 12’ silnylon tarp:
Many other fascinating vids by this outstanding lady, Carol Wellman here: https://www.youtube.com/results?search_query=brawny03
You can buy such a tarp eg from Aliexpress for around $30: http://www.theultralighthiker.com/ultralight-hiking-on-a-budget/ Hiking does not have to be just for the well-heeled!
Some other interesting shelter ideas here: https://ultralighter.blogspot.com.au/2008/11/under-this-shall-ye-sleep.html
The photo is a poly tarp version which cost around $10. I needed a few tarp clips to make it work. Five was the minimum needed. The extra short pole at the back worked very well to keep the tent material off its occupants. Some extra grommets along the side and front would be good. The latter for attaching your raincoat over the top of the doorway should you need to. You can buy the grommets and the grommeting tool for just a couple of dollars at army surplus stores and the like.
Or you could try this $10 tent: https://www.theultralighthiker.com/poly-tent-by-the-ultralight-hiker-on-the-cheap/
I have been sleeping under tarps of various sorts for around sixty years – and i am still here, so why not try one?
To conclude: If you are spending more than $30 on a tent (or carrying more than 1kg for that purpose) you are way over the top.