@plainoldme,
Hmmm... I usually wing it for these kinds of things... do you mean buying a pattern for a skirt with a waistband and then using the waistband part of the pattern? You could also just make a paper pattern yourself and make sure it's the right size, etc. Make sure to leave seam allowances.
3 or 4 inches sounds good, you could at least get the outside of the waistband the same fabric as the skirt, may need to line it with something else (as you say) depending on how wide you want the waistband to be. You might want to use interfacing too. Depends a bit on what sort of style it has/ you're going for.
You could probably have the whole thing be the same fabric if you cut off 4 inches and make the waistband 1.5 inches wide.