mindless I agree with you and most thread is more $4 unless you really search for deals. There is no thread in a LQS for $4. My hub occasionally asks me why I don't sell quilts or wall hangings, etc. and I told him that most people aren't willing to pay what I'd want to charge for my time making them. I also very seldom give anything away because most people don't appreciate the time and effort involved. I quilt and craft because it is very relaxing for me.

I went to Gatlinburg, TN. They were selling queen-size quilts in one store for $799, with label that said "handmade in China". As a quilter, I was appalled, because my handmade quilts are a lot better quality.
If cost is no object, give her the cost (plus profit for your time and work). If she really wants it, she'll pay it. If she says that it is too much, direct her to the site where you found it for a cheaper price. If it is mass-produced, it will not hold it's value as long, nor would she have something that a lot of time and effort went into.

I have found that if you turn your hobby into a business, then you are left without a hobby.

When asked how much I would charge to make..., I reply that I just make quilts out of love, not for selling.

I wouldn’t touch it for less than this or even more. You want to include extra fabric in case there is a mistake. You have not accounted for quilting cost. In our area edge to edge quilting is .$.02 1/2 per square inch. Binding cost is $.18 for machine bound and $.32 for hand binding.

I always insist the person come to the quilt shop with me after choosing a pattern. They choose the fabric with my help, thread, and backing. They know up front the machine quilter's cost and the cost of binding. After seeing all the totals on paper before my labor charge is usually enough for them to say let me think about it. Usually citing the indecision of fabric colors while in the shop. I rarely hear back about me making a quilt and I don't ask.