Just a couple of thoughts...
It may not be cheaper to buy your own fabrics (make your own kit) if the yardages are 1/4yd pcs and need to be WOF.
A lot of shops won't sell less than 1/2yd cuts so then you are buying twice as much as you need. Even if you can use FQs
some shops charge more for them.
I, and I'm only speaking for myself but I know danged well some of you can relate to this, have never purshased fabrics for a project that I didn't over buy. Usually because I have spent hours gathering fabrics from different shops (either in person or on-line) and once I got them together something didn't "work". Or I wasn't sure where I was going to use one fabric or another so I bought all 1yd or 1/2yd pcs just in case I wanted to change things around. Sometimes the kit price is not really all that inflated.
I have also bought kits that had wayyyy too much fabric. Never sure whether the shop or vendor was trying to make sure there was enough to cover for a mistake or just trying to get a lttle more money from me.
The book has several great quilts in it and if you can find it for sale you're getting more bang for your buck.
For a group of ladies always talking about "quilt police" I have to ask if there aren't a few undercover here but they are only concerned with what quilt shops and their owners can or cannot do. Show me where a kit is defined as fabric for the top and borders, fabric for the backing and binding, batting and the pattern. Oh, thread, maybe they "should" include thread. And just enough for this quilt, not a whole spool please. Nowhere, that's where. Those are preconceived ideas in your own worlds and not a "rule" or a "law". If you don't want to buy a kit because it doesn't have any of those elements that's fine, I respect that, but quit bashing the quiltshop owners. Times are rough for them too.
My guess is the same ladies that are horrified when Nancy Needleworker asks for a copy of their most recently purchased quilt pattern are put off because a shop owner won't copy a pattern out of a book to put in the kit.
And yes, >> would be one of those other unhappy customers if I had to pay for a kit that had a pattern or book included if I already had said pattern or book.
Now I will calmly descend from my soapbox and set off into the sunset.