The culture may be very different between vocalists and other musicians, so what I say below may only apply to instrumentalists. However, my daughter, an instrumentalist, has passed every prescreen for conservatory auditions. She has never had a professional prescreen recording. She’s done it herself using consumer-level electronics, a room with good acoustics, a good accompanist. When she was younger I helped out on the technical end by pressing buttons and converting the recordings to the right media, and so forth.
Her teachers have never been present during recording (it’s hard enough to arrange lessons, they are so busy) and have never viewed or listened to the recordings–not since she was 12 and applied to a national radio show program. Her then-teacher did come to that recording session, which was done in a hall in her music school. After that, always DYI, no teacher around.
She has also used some recordings/videos for prescreens. Her conservatory, which was also her precollege, does not allow taping in recitals, so for $100 or so you could get the recital recorded. Starting this year, they record for free. But there is no engineer, no soundcheck, just someone pushing the buttons. If the recital recording turns out well, there is no reason not to use it, although with an audition recording you often make a few takes and a recital is just one shot.
To be honest, I’ve felt nervous about this, knowing that many families spend thousands on professional recordings, but so far it has not been an impediment. It seems as though I’m now on the opposite side of the fence than in the other thread where I was criticized for being “naive” in saying that an audition committee will not overlook a nervous or flawed audition if they can sense the student is talented and well-taught. But a prescreen is a different matter. It is only a look to see who gets a shot at an audition. It’s not the first audition round. In some schools the prescreens are not even necessarily viewed by the faculty for the same instrument.
By contrast, for high profile competitions, a professional recording is important. I know that many potential contestants will have their prescreens heavily edited by sound engineers to produce a flawless recording. But college auditions and competitions are different types of auditions.
Of course YMMV, and you should do what you are comfortable with. But I don’t want students or parents reading this to think that all is lost if they don’t shell out thousands for prescreen recordings.