You not paranoid, I agree with Kimba completely, the first baby with the dirty vent is starving. She is extremely young and with no intervention will die before she learns to eat. At a guess I would think 28-35 days but may be older and growth retarded.
A teaspoon of ACV in about 200ml water daily will help. I am concerned about the dirty vent rather than the lack of feathers. The feathers are probably just separated and not missing due to dirt. She is tired and sleeps because she does not have the energy to play. Baby budgies are often very busy. Hand feeding formula or instant grams may even be a good idea even if only once a day. A human wheat cereal mixed with water can also be given. The problem is that no mixed stuff can be left in the cage too long. The vent area can be washed with plain water, maybe a good idea to see if the problem reoccurs.

The other 2 budgies appear in a much healthier condition, alert and interested in what is going on around them. I would guess the second yellow face blue to be female but I cant see the cere too well. The third budgie is decidedly male. The other 2 budgies are a good 2 weeks or more older, although I am trying to reconcile the cere of the second bird with the necklace they don't seem to match.

I called the vet today and got a quote on bloodwork/exam.

The store wont do anything about it, so its up to me.

Is there anything secific you think I should be worrying about/looking for?

Josh that is a real small baby there and it sitting funny hunched over is not a good sign. look at the bars on its head compared to the others.

I do hope things work out....I wish I could be more helpful ...

Baterial infections maybe water borne, pbfd and apv but those I doubt. Only reason I suggest is cos its good to know and there has been a scare again.

What is the chance of getting some rehydrating kiddie solution? I don't know names but it is a mix of sugars and salts, it will give instant energy. I still believe the birds biggest problem is too young too unweaned. Keep in mind that a baby out a nest box is not weaned as the father bird continues to feed after this.

do you think I should try formula and food and getting it hydrated all that you mentioned before a vet? or should I get him to a vet asap no mater what?

Angie, are you thinking of Pedialyte?

Yes I think Angie is right. Feeding something that gives her moisture & nutrition is important right now.

That little Dominate Pied [1st bird] is probably a female - usually the male, at that age, has a pink cere. Her posture shows she's weak. I hate the yellow discolouration on the feathers - sure sign of diarrhea. She is probably too young, or got ill & is too young, to recover without parental support.

The Apple Cider vinegar in the water will help with the bacteria in the gut & help a little. Make sure their water dishes are really clean. Lots of baby animals can go thru a bought of diarrhea but it is a serious thing & should be acted upon immediately. I'd make a list of the things Angie is suggesting & do what you can.

I would completely isolate her - until you are sure she can't share her illness via water & contact.

The 2nd is a male - [the pale one] - a Yellow face, Pied, Grey wing [just by being a grey wing - will lighten the colour of the blue]. I've seen people call these birds Rainbows. The yellow might indicate a double factor.
In one of the photos he was puffed up - is that because he was happy or is this common with this bird?

The 3rd bird is a female - Yellow face normal blue but the yellow washes over the blue in splashes - this may indicate a colour fault.

Supportive care is of the utmost importance! Extra heat, As to the pedyalite I've heard from vets that there is too much sodium in it to give to birds, But I do not remember what the alternative is. Some sort of formula will definitely help! If you do go to a vet I would definitely request a fecal gram stain, to look for a bacterial infection. As that would be mine main guess, other things could be a gardia infection, respiratory infection, ect. But my main guess would be starvation from being to young as previously stated or/and a bacterial infection. Baby keets can get bacterial infections rather quickly if the are underweight to begin with. And if things like water dishes are not cleaned well. Gardia also comes from tainted water, and some birds can pass it with out showing signs of it.

yes I did just not know the name

A vet may be an idea, but if the bird was mine I would support with Pedialyte, I have also heard not good for birds, but this is emergency and its not like it will be used long term. I would give pedialyte.

Maybe for 3 meals a day, one with pedialyte on with ACV and one with yogurt. Gardia type bacteria was also a consideration, but I think formula will change things. Normal parrot formula is often not rich enough for a budgie, but it is better than nothing. Adding crushed sunflower to parrot formula will satisfy and grow a budgie. In South Africa we can get a parakeet formula, if you have that get it. A small amount of yogurt once a day may also correct his system, it replaces the good bacteria.