Seashell looks gorgeous! Looks like good hair and none of it cut, and is she free of discoloration!? A really good Seashell can be worth upwards of $20+ because they're so hard to find in good condition.
Shady - $7ish, depends on flocking. Super good, you may be looking at a bit more.
Sunbeam - Depends condition, she's not a terribly valuable pony like Shady. 7ish again.
I'd get the bridle off of Peachy, stat, those can lead to saddle sores or the pink spots.
Twilight, again, a pony that usually hovers between $5-$10.
And then Ember, not sure, I'm not terribly well versed with baby G1's, but I would say you did fabulous none the less, especially on Seashell!