don't be a range slob. (although if you were a range slob, you wouldn't have asked about appropriate targets)
you can buy a metal base for target stands at most gun shows. stick a couple 1x2 wood boards in it (upright) and hang cardboard between them.
it's cheap, easy and durable.
alternately, you can buy a cheap plastic doohickey that stakes into the ground and holds cardboard. search a site like midwayusa for target stands and you'll find several options.
HOWEVER, depending on the range, i strongly advise not using them or any stand that places the target low, where it hits the flat ground. The point is that except in rare circumstances, your bullet should impact the backstop. Allowing your bullet to hit the ground between your "target" and the backstop will usually cause your bullet to ricochet instead of burying itself into the ground. If you can't see two impacts (one on the ground and one on the berm/backstop) then your ricochet is going OVER the berm/backstop and out of your control.
so, unless you're on a range that's built for that sort of thing, try to keep your target at a reasonable elevation.