Sweet clover: $25-30. $30 if it's the pink version, she is more sought after than the peach version.
Baby berrytown: she's a little hard to price. I've seen her sell for $20 but as high as $35. So I'm inclined to say $25 is a good price.
As for the twins. Sand castles and shovels are the priciest in my opinion. But really any from the 2nd set can sell for just as much depending on who is looking. But again in my experience, sand castles and shovels always out sell most.