When i contacted the ATO in regards to what was classifiable as income, i was told it was basically anything that you considered to be 'income' regardless of the amount.

If for example you made up a business card to sell blankets at the craft market, that is considered income and you should declare it on your tax return

If you sell things on ebay, and you purposely buy things cheap to sell them (not your junk from around your house), and keep a list of proft and loss etc, then that is also income.

There was some rumour if it was under a certain amount, (2k or 5k or something), then it doesn't count, which is not true, its all about how you view it..

The man did admit it was a grey area, which all depends on the honesty of the person.

If you considered market research or mystery shopping or whatever as a regular source of income, then it should be declared.

HTH