Excellent article here on leader design.
http://www.flyfishusa.com/tackle-tip...t-leaders.html
I've been using these tried and proven formulas building my leaders for 8-10yrs now(?) and cringe at the thought of paying $5-$8 for a factory tapered leader.Once you get past the initial investment of buying spools of Maxima from 4-30lb,I've calculated my cost per leader is about 75 cents/ea?
I generally build 9' trout leaders tapered from 25-6lb,then use 4lb tippet if required.I build 12' salmon/steelhead leaders tapered from 30-10 or 8lb,and I can "cast" them and have them unfold straight to the tippet in the house with just my arm and the butt section held in hand.....that's with no fly tied on.