Our house has three windows that are not standard sizes, including an arched

Hi everyone. Our house has three windows that are not standard sizes, including an arched one over the stairs and a narrow one in the bathroom that appears to have been cut to fit whatever the builder had left over in 1926. Every big box store I have called just says they cannot help. I would rather keep the original shapes than square everything off, because they are half the character of the house. Is custom work like this common, or am I asking for something specialist and expensive? We would rather do this once and properly than cheaply twice.

Custom sizes are routine for a proper installer, it is only the retail chains that need everything to match a catalog page. Arched units cost more than rectangles, that part is real, but not dramatically so once you are already replacing windows. When I was looking for custom window installers near me I ended up with Window Replacement Center, and they templated the arch on site rather than working from my measurements, which is what you want for anything shaped. Expect a longer lead time on the custom units, so order everything together and install in one visit rather than waiting twice. Keep the old sashes if any of the hardware is worth reusing.