MG T-ABC

I wonder if someone can assist me please ? this came with a Bluemels Douglas wheel I purchased for another car.. I have no need for it and would like to sell it.. BUT I don't know what is fits or what is a fair price to ask for it .. anyone ?

That's an aftermarket center cap. I'm trying to remember who made them, maybe Bell Accessories, or Arnolt? They aren't terribly uncommon, in fact I have a couple here somewhere. I'd say if you found someone who just had to have it, and couldn't find another one t that time, maybe $60? If I were buying one at a swap meet just because I needed an interesting paperweight that wasn't heavy enough to hold down paper, I'd pay maybe $10-20. But that's just my opinion.