Fraza
Yeah, it is rather difficult... I'm in the same boat, and sold over half my birds a few months ago. I decided to keep my family of society finches since they're my highest-quality birds, and ended up selling all of my Javas and gouldians, as well as my infertile society and her mate. Even taking a loss on the gouldians (female should not be bred), I managed to break even in regards to original buying cost.
If you don't already have a buyer, good photos can make all of the difference. I got around 10 offers within a week of posting, and was able to sell all of the birds to the same person; they have several aviaries, and said they would keep all of my birds together.
Since you have a lot of birds, you probably don't need photos of all of them; just concentrate on one or two of your nicest birds of each species that you're selling.
I brought each of my birds into my bathroom one at a time to take photos. I dimmed the lights, put a white board behind them, and sat them on a branch before taking a few photos (usually around 5 per bird) with flash. My birds didn't seem to mind the flash any more than regular photos, although I would not recommend using it for red-eyed birds, as their eyes are more sensitive. Flash also makes colored birds like gouldians look weird, so non-flash may work better for them, although those photos will need to be taken in bright light or they will come out blurry.
Don't keep the birds out for more than 5-10 minutes, and put them back soon if they start panting or otherwise freaking out. Don't post photos of panting birds or birds with closed eyes or droopy wings, as the buyer may think they are ill. (Obviously don't sell ill birds, but stressed ones can look like ill ones, and many birds become stressed while you are taking photos.)
Take the photos into Photoshop or another photo editor and correct red eyes (unless the bird's eyes really are red) and adjust contrast and color balance to match the photo with the bird's true coloration under normal light.
Do you know exactly which birds you're going to keep; what are your priorities? My priorities were keeping pairs together, high genetic quality/fertility (so no on the gouldian pair and infertile society), and cleanliness (no for the Javas, since they threw stuff everywhere).
I wish you luck with college and the job!