Chimney chase covers

Last year we had a new SS chimney run on the side of the house. We finally got it enclosed and are going to start finishing the outside with stone veneer-hopefully before it gets way too cold.
We need to get a chase cover. When I called my installers, who are coming to measure since this is a custom job, I asked a rough price. Pretty sure the area is 4'x2.5'. We were thinking $5-700. Rough estimate with installation, and no true measurement, was $1500 from the installers.
Is that a bit insane? Of course everyone else is too busy until mid- November to even come a give us an estimate and our guys are squeezing us in. We may be at their mercy. I just want to use my damn stove

I know it is a bad time of year to be dealing with this but our contractor who was going to enclose the chimney didn't get to us until last week, though we spoke with him back in June! Not worth telling the story....

I would prefer SS over galvanized so I understand the cost difference. I'm sure the installation would be included in that price. Hoping they make it out here today to measure to get this started. Getting the chase cover would be the final inspection to close out the permit on this ongoing saga of the chimney. What started as a routine cleaning last fall turned into a $15K nightmare that I just want over with.

Thank you!

Got the price back from the chimney guys and it is much cheaper than they originally estimated even with the install. $550 plus installation. I have no idea where they came up with that first price but glad it was a giant mistake. I knew it shouldn't be that much.
Chimney chase got scratch coated yesterday and the stone should be started tomorrow. And our chimney nightmare will finally come to an end!