find a local welder willing to do it for a case or two of beer, 35 dollars worth of chains and s-hooks and your good to go. 1 1/2 hooks and 2/0 long straight link chain are the industry standards. i made my own before I turned it into a business (im a welder and engineer as well as a very crafty guy), my first attempt was good but our current product took 100's of hours of research and engineering and jigging.
but your are better off buying something like the m14 and adding some extra chains if your not ready to buying a full size portable. it'll last a lot longer than a portable of the folding variety and you kick yourself in the ass if if you spend 50-60 bucks on parts plus hours of assembly to end up with a POS crappy looking homemade basket.
just my 2 cents (but i know what i am talking about)
Save yourself the time and effort! For the cost of material needed to build a basket, you can buy an InStep basket on line (less than $100 including shipping). If you add an inner set of chains, it will catch disc with the best of them.
I found a cool video on Youtube, and i went to Lowes with my shopping list. I couldn't wait to get started. I added up my receipts, and found I'd spent 150.00 before chains. Took everything back, ordered an M14 which is light and sturdy enough to practice with.
I saw one on YouTube where the guy uses a bike rim, some chains and a pole. Maybe not the greatest basket in the world, but I'm sure it didn't cost much especially if you can find an old bike rim for free. Viva YouTube!