Traditionally artists have looked towards New Zealand on Air’s single budget ($5,000 + GST) as a rough estimate for what a professionally single recorded should cost. The emphasis here is on professionally RECORDED. This figure concentrates on the recording aspect of a single and unfortunately does not take into account what a producer can bring to the table with regards to song, sonic direction, arrangement, contacts, and the work involved to complete a recording which has a higher chance of commercial success.
You could argue that if a song has received this funding then it should probably have a good chance of commercial success anyway but if you look at the statistics as to which songs have a life after NZOA funding then more often than not they are the ones which have involved a producer.