I use both also, and the steel is definitely more fun. The cheapest, quickest, and most portable setup i could think up was the following--
Get 3 pieces of rebar (or some such steel rod). Pound 2 into the ground. Get a couple copper or galvanized plumbing T's from the hardware store, and set them on top of the rebar. Lift slightly and slide the 3rd rebar thru them parallel to the ground. Now attach steel with S-hooks (keep an eye out while driving down the road. A lot of people lose those tie down straps with the big S-hooks that are closed on one end, or the rubber bungees with the little S-hooks too. Be careful with this 1 tho--a lot of wives don't like it when u stop on the road to pick up "trash."
Here's what i use in the field for long-range paper tgts, that's again, super-portable (can carry 20 in the truck if u want to), super cheap, and quick to put together--
Get 2 pieces of rebar again, 2 pieces of 3/4 electrical conduit pipe, a pack of long zip straps, and cardboard of any size. Attach the cdbrd. to the conduit with the zip straps all along the edges. Now u can pound the rebar into the ground and set the tgts. over them, and voila--even stands up to some pretty good wind. Make any size tgt. u want. I also have a couple cdbrd. templates made with circular tgts. cut out of them, and i get that el-cheapo Wal-Mart paint that's 99cents/can, and paint the tgts. on the cardboard/steel.