Question about Non-Magentic Fly Away Batman and Robin

[Overkill]

I'm still a newbie to Mego prices, and I was wondering what would be a good price to pay for one of those Non-Magnetic Batmans and Robins boxed?

Also, I've been on the hunt for a 9 1/2'' foreign Mego Robin, but I'm not sure how much I should pay for a loose one. Can anyone give me a rough estimate of what I should offer without going overboard on the price?

Thanks!