I picked up my second cot mosquito net at Fleet Farm the other day, this one came with poles. Cost for these is usually around $10 for just the net a couple or three dollars more with the poles. I could care less about the poles to be honest.
I like these because they make up part of a lightweight shelter. I've used tarps to make a lean to and other tarp based shelters but the one reason I really prefer tents is the bug netting. With a mosquito netting for a cot I can have protection from the bugs in whatever shelter I make.
One tarp, one thermal blanket and mosquito netting rolled up with 6 stakes and some line makes for a lightweight and flexible shelter. If I have a hammock I can keep myself off the ground, reflect body heat back up to myself, have shelter from wind and rain and keep the bugs off of me. Even with the hammock I am looking at less weight than all but the lightest (and most expensive) tents.
Cost for a basic tarp is around $10, the reflective blanket and mosquito netting also cost $10 each. Parachute cord and stakes are under $10. Total cost is about $40 for a shelter that has many options and more uses than just shelter. I like tarps that are 7x9, 8x10 or 9x11 (measurements in feet) in size.
There are lighter weight tarps out there, like silnylon and similar materials but I use a basic poly tarp to keep price down. Maybe I will get a silnylon tarp in the future, but the cost is a bit high for my tastes at the meoment.