this is the time of year i start to see so many people bring new babies into their homes. Unfortunately, some people think it would be fun, save them money,a great learning experience and an opportunity to bond with a new baby by purchasing one unweaned. I can assure you this is unfounded! 
i  as a breeder( no longer breed now), never sold one baby that left my home unweaned. Ever! I  don't care if the person who purchased a baby from me was a breeder  themselves. It was my responsibility to make sure my babies were well  socialized, weaned, fledged and ready for their new homes. It has been  proven that purchasing an unweaned baby does not promise a better bond  with your bird. Many things come into play. How the baby is taken care  of, socialized and hopefully abundance weaned at the breeder"s. The  parents of the baby can genetically influence the personality of the  baby.  When baby birds mature and reach an independent age they leave  their parents. So it is quite natural for them to form new bonds as they  grow. Coming into a new home as a fully weaned, well rounded baby will  tip the scales in the positive direction.
A responsible, caring breeder will not sell an unweaned baby, ever! Let  me clarify this by saying a baby that leaves their home before being  weaned and fledged. I always welcomed new owners to visit their babies.  And all of them did. If they balked a red flag would go up for me. Never  would i allow a new owner to handfeed their baby in my care. There is  absolutely no purpose to it! I wonder how many of us get to bottle feed  our pre purchased puppies and kittens? 
So lets say you purchase and unweaned baby on 3-4 feedings a day. Here  is what you will need to absolutely ensure you are heading in the right  direction. 
A brooder-either homemade or pre-purchased-set up and ready before baby comes home-$50-150
formula, syringes, thermometer-to start $50+
an avian veterinarian for when things go wrong-$75+ per visit
the baby will need to eat every 3-4 hours from 6am to 10pm. Not when you want to feed baby but when baby is ready to eat.
Prep, feeding, brooder clean and clean up after feeding you can count on 45mins-1hour
now remember this is barring any problems that arise. Aspiration, slow  crop, yeast or bacterial infections, burnt crop, baby falls off table  while your head is turned, (yup it happens!) when a baby aspirates it is  horrific to witness! They squeak, flap, rush at you and drop dead. End  of story....how do i know? In my 15 years as a breeder it happened to me  twice. It was tragic and i will never forget it.
When having a baby to handfeed you must plan your day around the baby's  feeding schedule, not yours. No vacations unless you plan on taking baby  and brooder with you. Oh! And don't get sick! There is nothing worse  then prepping and handfeeding while you are running to the bathroom  throwing up!! 
You want the experience of hand raising your new baby but do you want  the experience of seeing it ill, paying hundreds of vet bills and  possibly seeing it lying dead on your table because of your mistakes? I  hope not.
You think you are also saving money because you will finish the weaning.  Take into account the formula and supply costs. The vet bill when  something goes wrong, and it will! Your little cockatiel that cost you  $75 could end up costing you over $300+ easily.i know because i have  been there too!
As babies grow and fledge and it so very important to socialize them. Allowing them to fly for several weeks prior to clipping(if you wish) is extremely important. Flight helps build self confidence, strength, balance and muscle. Taking that ability from them at such a young age is extremely harmful to their development and future as a companion bird. 
  Great breeders will not be so selfish and try and cut  corners or look for the easy way out. The breeder who sells an unweaned  baby are just as guilty as the buyer who wants to save money or  "experience" handfeeding their little charge. In my opinion and  experience it is just not worth it! I have cried to many tears and i  hope you will think twice before you may too...