Hubby and two of his friends made climbing ladders out of metal. They used square metal pipe and rebar. Basically they look a lot like this:
http://www.lancasterarchery.com/shop...2acbf161780a88

But, since one of them does a lot of metal work and had the shop and the three of them split the cost of materials and labor between them, it came out fairly cheap. They are in sections of about 4 or 5 feet so you can use as many as you need. And you can take the bottom section (or two if you prefer) with you so someone else can't use your stand.