I use and tie my own knotted leaders. This is not really a cost saving plan. Instead, I believe its a more effective way to manage clients leader issues. I tie a stock leader being a 9' 4X leader. From this I can add 3' of butt section to make a 12' or better leader to fish the Battenkill. Or I can cut the butt back to make a short leader to fish mountain brooks. For lighter tippets...5 or 6X....I cut the 4X tippet on the stock leader and add more or lighter tippet. Here is the leader formula I use:
Knotted 9 foot 4X leader:
Butt 36" of .019
16" of .017
12" of .015
6" of .013
6" of .011 (0X)
6" of .009 (2X)
tippet 26"of .007 (4X)
Replacement mono or spools of mono I have in my vest for leader repair or tinkering:
.019, 0x, 2X, 3X, lots of 4 &5X, 6X and in August 7X.
Best bet if you are going to build some leaders is to buy a leader tie kit. Another advantage to tying some of your own leaders is the practice at knot tying....will help you on the water.