It's a matter of what an angler can work with comfortably. With sinking lines and short leaders I don't bother with tapering the leader. I have known guys happy to fish a single 10ft piece of 4x... kind of wasteful though.
I don't use more than a few tapered leaders per year. I mostly buy them but you can tie your own and the good news is they are both easy to tie and to repair. You don't have to toss a leader that has a few wind knots in it or where the tippet is gone. Just cut out the knot or tangle and reattach with a double surgeons knot.
You can buy a standard size ...say tapered to 3x and then add thinner tippet as conditions warrant. For anything over about 2x I just tie my own.
Download leadercalc;
http://globalflyfisher.com/fishbetter/leadercalc/GFFLeaderGuide.pdfhttp://globalflyfisher.com/fishbetter/leadercalc/download.phpfor a plethora of advice and leader formulas.
For most leaders I just use the easy to remember Flip Pallot design:
half the length of the desired leader length: for 10 feet 5 feet of 25lb of butt material
for the taper: step down 5lbs and 1/2 the length from the previous section: ie 2.5 feet of 20lb, 15 inches of 15lb, 7 inches of 10 lb then 18 inches of tippet - 6 to 8lbs . If you need a lighter tippet just ad 6 inches of 8lb then the tippet.
Measurements needn't be exact.
For dry fly or emergers the Borger formula is easy: 4 to 5 feet of butt material (say 20lbs) 1 foot of taper (say 10lbs) and 4 to 5 feet of tippet.
You don't need expensive mono just about anything work.
All you really need is to be able to tie a double surgeons knot and a blood or barrel knot.