$400 is a very good deal on a nice Leer topper. Around here that topper would sell in the $650-750 range if it is a popular color and fits a popular truck.
What color is the topper and what truck does it fit?
To get it painted is very expensive if you want it done right so it looks good. By the time you are done it will cost more than a new one in the right color.
When I got a new truck last January, it was a different color and I had the Leer painted to match, cost me $700 but looks perfect. A lot cheaper than a new $2400 topper
