I found this DIY bracelet here (click for full directions) and i thought it seemed easy enough (it took me an hour). You can find all materials at your local Home Depot. It cost me less than 10 bucks! and turned out great!. I asked the guy at the Home Depot for rope and he suspiciously asked, "what will you be using it for?" and i replied "well not to tie anyone up with".
TIP: You might want to tie one end to a pole or something sturdy in order to braid it.