A monitor with accurate color reproduction that's good enough for professional use will run you at least $1,500, probably more.
E.g. DELL Premiercolor 27" 4K:
https://www.dell.com/en-us/work/shop/dell-ultrasharp-27-4k-premiercolor-monitor-up2720q/apd/210-avbp/monitors-monitor-accessoriesCheaper monitors aren't useful for professional-level photo editing, even when calibrated (out of the factory or manually) because they either can be bright or accurate but not both at the same time--which isn't a problem for most applications, like office stuff or gaming; but for photos it is.
There's a reason the best monitors cost a lot, e.g. the Apple Pro Display XDR has 32 inches in 6K with full P3 color gamut w/ 10-bit color and is super bright but also will set you back by at least 5 kilodollars.
That said:
* Get the monitor with the widest color gamut and bit-depth you can afford
* Get the highest resolution possible, for astrophotography you will often have to deal with stars which sometimes are only visible in a single pixel in the data
* Work in a darkened room, this makes it possible to turn down the monitor brightness and gives better colors on cheaper monitors