So I was trying to calculate how much those precut fabric bundles really cost and I came up with this...
layer cake, about 42 ten inch squares equals 2.34 yards of fabric.
Average price of fabric $7 a yard
2.34 yards = 19.25
price of layer cake about $35
I based these on info from a reasonably priced fabric site and going by Moda fabrics.
That makes the layer cake fabric about twice the price of the cut fabric. Can this be right? If so someone is making out like a bandit. Now I can cut my own fabric squares. Precuts are nice and convenient but from now on I will rethink my purchasing options. Please someone correct me if I am wrong.

Look at all the different fabrics that come in layer cakes.

Yep, you are paying for someone else to cut them, and coordinate the fabrics. I only buy this type of fabric if it is on sale for a really really good price.

Sounds about right to me. It is all about whether you like the convenience or not. I happen to like the layer cakes or charm squares because I get lots of coordinating fabrics without buying fat quarters. You can't get 4 10" squares from a fat quarter. I find fat quarters for me a waste. I would rather buy a half yard of something so I have the full width of the fabric. I only get the charms or layer cakes when they are half price.

A) I never pay full price for the pre-cuts -- there are good sales out there, and I take advantage of them.

B) You have a huge convenience in getting a wide variety of fabrics that all coordinate, without having to buy yardage of each. So for those of us who can't/won't/don't build stashes, they are a good choice.

C) When you buy small amounts of yardage, you are at the mercy of your cutter. The last 1/3 yard cut I worked with had a significant wave in the cut, and I lost almost 5 inches of usable fabric when I straightened it. The pre-cuts from reputable fabric manufacturers are beautifully straight.

D) Not everyone does well with cutting accurately. If poor cuts lead to bad piecing, frustration, and giving up on a project, which then languishes forever in a closet, you have not saved anything, and you've lost a lot of enjoyment in the hobby.

So precuts may not be for everyone or for every situation. But they are a convenience that makes sense for some people in some situations. I like using them for scrappy quilts w/ a coordinating line. But I can't see myself buying the single fabric jelly rolls-- like a roll of 42 white solid strips, for example. Those I can cut on my own, and pay a lot less doing it.

RST

I have tons of precuts. I love them. I don't have a stash. Precuts work best for me. :)

It may sound expensive. You have many different fabrics in a bundle. If you had to purchase 1/4 yd of all the different patterns, that could be very expensive too.

I started the math with fat 1/4s some of those prices were outrageous, mulitply price by 4 and you get high dollar yardage,and now I never buy anything pre cut, it is strictly economical with me.

I have only bought the charms when they were $2.xx each. 25 in the pack....so I thought that was a great deal! :)

Average prices I've seen are closer to $9 or $10 a yard. Still, it's no secret that with precuts you pay for the convenience of having it cut plus the variety. I have trouble cutting so for me, it's worth it. Plus like someone mentioned, I never pay full price for them.