Supply line to ice maker and shut off valve

My freezer had a plastic supply line that sprung a leak so I want to replace it with a copper line. There was an existing piercing valve that was installed that I think should be replaced by a shut off valve.

What should I expect the cost to be for a plumber to run about 15-20ft of 1/4"copper line and replace the piercing valve with a regular shut off valve?

You should expect to pay what the job is worth and not a penny less.

The value of all things contracted for, is measured by the appetite of the contractors, and therefore the just value is that which they be contented to give.

THOMAS HOBBES, Leviathan

Chicago is a fairly high cost area. Estimates can vary radically from region to region and plumber to plumber. It shouldn't take more than an hour IF the water can be turned off and things drained in a reasonable time. If this is a high-rise, or a place where the shutoff does not work to completely shut off the water, it can get time consuming. The piece of pipe where the current valve is located should really be replaced and to do that requires soldering. You can't solder with water in the pipe - it won't get hot enough, and the steam can make for a leaky joint. This all takes time, and time is money. Also, if you need a permit, that will add both time and therefore expense.

It is for a single family home.

The quote I received was $550, which seems extraordinarily high for what they said was 2 hours work.

You have to realize that you are paying for the shop's overhead as well as 2 hours labor. That is probably a fair price, but it's why many of us learn to DIY relatively simple jobs such as this.

They quoted $550 for running the copper line and replacing the shut off valve.
It was $250 if they just replaced the line and used the existing valve. I think what is in there is a piercing valve so I might want to replace that anyway.
$300 to swap out the valve seems like a lot.

I understand needing to price in some of the overhead.

Either way thanks for the insight. Just wanted to check

Keep in mind, many shops start the timer when they leave the shop, so depending on how far away they are, that can add up to quite a bit. Some places do time and materials, some do fixed price, and some will do either. With a fixed price, you shouldn't have to pay more, but you won't pay less if it goes easy. With time and materials, they don't have a big incentive to work fast, but depending on the job, if it is easy, you can save some money. There's a risk, but if, say it only takes them 1/2-hour when they budgeted for 2, on time and materials you can see how it might save. But, if they run into complications, on time and materials, it might take 4-hours, and then your costs can skyrocket. Both sides are gambling, depending on which method you choose.

i won't weigh in on price...it is what it is...i'm with tom there...but i would certainly recommend getting rid of the needle valve for a proper shut-off