I have heard of 'Mercy' clothing in recent years and understand them to cater to the Goth/Bondage fraternity (NOT my scene, I hasten to add!!). I believe they are a British company and, whilst I cannot find a website in their own name, I have found this retail stockist who lists several of their garments - this being the link to a plain black kilt:

http://www.katesclothing.info/produc...Black-Kilt.htm

What one might expect for £25.00 I shudder to think, but it might be fine for washing the car in (or with!!)