I can't help much, but I'd guess about $8-10 for the wands, $2-3 for the sea pony brush, probably $1 on the pull toy and the bridle. Probably $2-4 for the headband, and I can't quite place that baby necklace, common ones go for $1 or so, rarer colored ones $3 or so, but I've never seen that one!
I have no idea for the lavender castle accessories and the rest, maybe $4-5 each? But I'd be interested in 2 of the fence pieces for Megan's Place, and the trough.