Kits are worth every penny unless there is a large upcharge for them. When should you buy a kit? When you want THOSE COLORS. Depending on the type of quilter you are, sometimes it isn't the pattern that attracted you to the quilt, but the colors/designs of the fabric. In some cases, you may not be able to get the feature fabric any longer unless you buy the kit. In those cases, a kit is worth its cost. You have everything. You can start right away.
When is a kit not right? When you always change things. When you want to use much less expensive fabrics. When you want a different colorway. When it is the pattern, not the fabric, that is pulling you towards that quilt.
If you are beginner or simply have no stash, a kit may or may not be the difference between sewing tonight or sewing sometime next week.
As you can tell from my response, I do sometimes buy kits. USUALLY it is because it is on clearance and marked down, but I have 5 or 6 quilts that I bought as a kit because I wanted THAT quilt with THOSE colors. While my checkbook complained, most kits include more fabric than you need, but they include ALL the fabric that you need (unless stated - sometimes you have to provide backing or binding).
edited: One thing to add. Don't put off doing your kit for eons. While the shop is willing to providing you any missing pieces, the last kit I bought was from a shop that closed 2 months after I bought it. Had I been short on fabric, I would have been out of luck.
Last edited by IAmCatOwned; 09-26-2013 at 01:59 PM.