>>983443A mansion is in some senses a tent that's just really expensive and difficult to carry. A plastic bag is similar in an inverse way. I'm so glad didn't include any sort of specs, requirements, or price tag because that makes this super easy.
I think you should get a tex-sport scout. It's $30 and you can sleep in it a few times and figure out what you want in a tent. Or sleep in it a few times and realize you don't need anything more. I personally use a blue fuckin' tarp and a bug helmet/jacket I picked up for 50cents a piece at a garage sale if it's necessary.