I thought the thread was about the regulatory issue, not what was safe and/or smart. VH-XXX seems to have pointed to CASA's view of the convoluted words in the current regs.
The regs don't specify a minimum height for straight and level unaccelerated stalls, this is true. What is the motive behind this thread though, to mandate they impose a minimum, or a student trying to save a few bucks and argue with their instructor, or are there instructors out there scaring students at low level and the students are asking for advice on the actual rules.
Imposing a minimum is type specific, so one altitude can't be deemed safe for all. Recover by 3000ft is a good starting point as you have lots of room if it gets worse than anticipated. You also run into problems if you mandate no stalls below 3000ft and your aircraft requires it to land. I will add a well trained competent pilot can stall and recover with very little height loss safely without much chance of an adventure in an aircraft he is familiar with. In the case with most flying schools/colleges in Australia the normal situation is unfamiliar/inexperienced pilots being taught how to fly, operating close to the stall with these students can result in very rapid loss of control.
Saving cash during training is more about smart planning and study than 10 minutes climbing on one or two lessons.
I have heard of instructors performing manuevres such as stalls at low level and almost coming to grief, scaring the student and the student reporting it. Its not worth it from an instructors point of view, whilst you are on board and even to a point whilst the student is solo you are responsible.