Alright time to try and help.
G1 ponies-
Morning Glory; Assuming she has no tail rust, symbols are nice, hair is not dry, and there are no paint scuffs I'd say around $5-7 USD. There seems to be a head and body mismatch, her wings are broke, and I think I see an age spot on her. If you have her original wings her price could probably be more around the $7-9 USD.
Sparkler; Assuming she has no tail rust, hair is not dry, and no paint scuffs I'd say maybe $5-7 USD. She seems to have a bit of a hair trim, very slight head and body mismatch, her horn might be bent slightly, and her blush seems to be gone. HOWEVER, her symbols are very nice and she is overall very clean.
Moondancer V1; Assuming no tail rust, hair is not dry, and no paint scuffs I'd say maybe $5 USD. She is either yellowed or very dirty, however her symbols look nice and she has great blush.
Half Note; Assuming no tail rust and no paint scuffs, maybe
maybe $5-8 USD. There is head to body mismatch and her hair is majorly frizzy. She is worth more than the other ponies because from what I understand, she is a tad bit harder to find due to a later release. I'm not saying she's rare, but not as majorly common as Moondancer or Sparkler. If you can find her guitar brush, then maybe the $8 for sure.
Sunlight; Assuming no tail rust, hair is not dry and no paint scuffs I'd say $2-3. This pony is bait sort of. She's not horrible bait, but shes not in the best condition either. Her tail has been cut, she is dirty, she has major symbol wear, and she has symbol rust. But at least she has nice color and blush?
Sherbert; I have no idea where to price her but she does seem to have some discoloration so take that into consideration.
Heartthrob; Assuming no tail rust, no paint scruffs, hair is not dry $5-8. She has good color, her symbols look nice, she has some factory curl left, and her blush looks nice.
Cotton Candy; If she is a concave foot, maybe $2 if a flat foot maybe $3. She is missing her tail which can be a major factor to some buyers.
Firefly; $3. She's missing her tail, blush is worn, and it seems like she has a haircut. But her symbols looks really nice.
Moondancer V2: $2. Missing tail, ear is yellowed, hair is cut, blush is worn, symbols worn.
Glory; $2-3. Her hair looks nice! But she is yellowed, tail is missing, symbols are worn, and blush is worn.
Your best bet is to either fix some of these ponies up or sell them in a lot.
I can't help with the G3 ponies. But the first pinkie's hair is faded which will probably decrease from her overall value.
I hope this helped you, this was sort of a fun exercise to do!