Drug information was at the more serious end of the scale in terms of police payments.
"The fund is used surprisingly little as the cash isn't a big motivator," the source said.
"Informants are usually connected to the criminal element and their motivation is most commonly revenge."
Graham Bell, a retired detective inspector and frontman of the Police Ten-7 television programme,has seen many motives.
"Not all do it for money, sometimes they just want to see the right thing done. Sometimes it can be disgruntled husbands or girlfriends.
"Some just do it for virtually beer money, and others realise they are in possession of something police are going to find absolutely vital, and do their best to extract as much money out of them as they can."
Over his career, he had seen murder inquiries cut by weeks because of intelligence from informants.
The informanat programme has not been reviewed recently, but police national crime manager Detective Superintendent Rod Drew said it was under "daily operational supervision" throughout the country.
"Informants save considerable police time and resources because quality information allows police to concentrate in the right areas against the right offenders. Any investment is made on the basis of results, not promises."
Police Association president Greg O'Connor said curtailing the programme would not "in any way" be in the interest of the public and would only benefit criminals.
"Defence lawyers in recent years have gone to great effort to discredit informants and the programme, which is purely to benefit their clients but does nothing [for] the public."
He saw using informants as "an essential part of policing".
"These days, most criminal groups are well organised and are very sparing of the information that comes out of them. They're also very aware of electronic surveillance and a lot of the better criminals will be very careful what they say over the phones, so often some informants are extremely valuable."
Mr O'Connor said only certain types of police officers were equipped to run informants.
"Because [informants] have to be living those lifestyles themselves, it's always an area you have to be very careful in."
The Herald was refused most details it sought about the programme, but under the Official Information Act was given the annual amounts paid to what are termed covert human intelligence sources.
Senior police staff were able to approve varying amounts depending on their rank.
There was no set limit on what Police Commissioner Peter Marshall could approve, deputy commissioners could authorise up to $25,000, finance general managers and district commanders no more than $10,000, while the limit for crime services managers was $2500.
Police would not reveal the biggest single payments, how many informants they had, whether they received retainers or expenses, or details of prosecutions resulting from their information, for fear of identifying informants or revealing the programme's methods.
INFORMANTS' PAYMENTS
* $271,111 in 2006/07
* $430,178 in 2007/08
* $446,845 in 2008/09
* $400,239 in 2009/10
* $343,057 in 2010/11
* $268,259 in 2011/12
2011/12 represents figure for the financial year to March 2012.
