Regarding making your own....

If you have access to someplace where you can set up an apparatus and leave it, then you are really lucky. I spent about 4 hours thinking this over, and if I KNEW that the stuff I set up was going to stay where I put it, this is what I would do.

I would scrounge two, six foot galvanized fence posts. They're everywhere. Fence posts, traffic signs, Parking lot markers, these things are ubiquitous. Old ones get tossed all the time. An hour of looking will surely turn up one or two...you'll need two.

Now go down to the hardware store...Orchard Supply or Home Depot or Lowe's and get two, ten foot long, one-inch electrical conduit section. This will cost about eleven dollars, each. Get two, two-inch long , 1/4 inch bolts, and nuts to fit. Also get two light-duty pulleys (about $4.50 each) , 50 feet of cheap nylon rope (about $4.50) and a 5 foot length of PVC or ABS pipe, maybe 1 1/4 inch stuff (about $3.00). Get four of those contractors stakes I was talking about...$16.00 or even two, three foot sections of 1-inch rebar.

you're going to sleeve the electrical conduit inside the fence posts so theres' about a foot of overlap, drill through the sleeved section with a hardened 1/4 inch bit, and then slide the bolt through. This will make a 15-16 foot long pole, and you'll have two of them. Disassemble after checking the fit, while you're putting it together, and assemble at the site when you're ready.

OK, at the top of each piece of electrical conduit, about 1/2 an inch down from the end drill a hole and put in an eye bolt. You could also use a cable clamp to put a D-Ring up there. Now put a little pulley up there.

Haul everything to your site. Drive the contracters stakes/rebar into the ground absolutely straight up and down, about 5 1/2 or 6 feet apart.

Assemble your poles with the 1/4 bolt. Run the rope up one pole....through the pulley...down...through the pvc/abs pipe....up...through the other pulley. Tie it off to the galv. fence pole somewhere.

Now, two guys working together lift up the poles and drop them down over the contractors stakes/rebar that you drove into the ground.

VOILA.. WOB uprights, adjustable to 15 feet. The bar swings, because it's a 6 inches - foot narrower than the space between the poles. So if you smack a weight into the bar, it will just swing out of the way and won't break.

If you really have your stuff together, you'll paint marks on the poles every foot, so that you know how high the bar is.

This whole assembly is reasonably sturdy, cheap, and you can take it down at the end of the season and store it in the rafters of your garage, or throw on top of the roof rack and haul to the Games if you ever need to.