I spent some time on Ebay looking at capes like yours. When I looked, I did not include older Whiting/Hoffman type capes, which tend to sell for more, nor did I look at non-name brand capes.
I looked at capes by Metz, and similar brands.
Capes in like new shape, in natural colors like Ginger, dun, brown, griz, etc., which look good in the picture, aren't picked over or out, and are obviously a high quality cape, tend to go for around $30.
Capes that are either picked out, are in an odd dyed color, have an odd shape, etc., go from a few bucks to may $10 or so.