I disagree, they are worth $1-2 in the condition you provided. But only if you sell to me.
Kidding aside, I agree with the $65-75 mark! $70-75 for the two unicorns, $70 for the two Pegasus and $65-70 for the two earth ponies.
MIB I would say $100-150 I sold a mip baby up up and away for $140 a little while ago.
I would suggest auctioning them, lately the unicorns have been hitting high prices!