Are you looking for something pretty lightweight, well designed, but perhaps also a bit expensive? Heck, on the really inexpensive side I guess you could just go to your local hardware store and buy a tarp with grommet holes ...

For somewhat higher end there's still quite a range, from what Campmor offers, to Mountain Laurel Designs, Gossamer Gear has some options, you can look at tarps from multiple companies at sites such as Prolitegear.com or Backcountrygear.com.

Maybe I'm misunderstanding what you mean by "pup tent" ...