One of the assault rifles used by killer Martin Bryant in the Port Arthur massacre sold for $89 in Australia in the 1980s.
China made thousands of the SKS semi-automatic weapon which were exported worldwide to earn much-needed foreign currency in the 1980s.
Former Australian gun-maker Don Jones said from Tasmania that he could recall the guns selling for $89.
"China flooded the Australian market at an exceptionally cheap rate. They created a problem of dumped ex-military weapons," Mr Jones said.
"The SKS was not such a high-powered rifle compared with other but it was popular because it was cheap."
The SKS was a 7.62mm calibre weapon that could shoot bullets at 735m a second. The gunman's other rifle, the 5.56mm Armalite AR-15, fired at 1000m a second.
Mr Jones said the cheapest guns tended to be used for crime. His former company Australian Automatic Arms made weapons costing $1000 but were bought out by the Federal Government four years ago to curb proliferation of such weapons.
Military style semi-automatic weapons were also outlawed by Canberra and the popularity of the SKS waned. But many examples are thought to be in circulation.
WA is believed to have 70,000 unlicensed weapons although how many are semi-automatics is unknown. One in five WA homes has a gun.
Importing a firearm into WA requires police clearance. State laws outlaw military lookalike weapons and semi-automatic firearms without integral magazines.
WA's laws, rated Australia's toughest, allow low-powered .22 calibre weapons and .22 semi-automatic rifles with integral magazines.
Australian Customs Service confiscated 1800 prohibited goods last financial year but it is not known how many of these were guns.
The Police Federation of Australia and New Zealand called yesterday for uniform gun laws in Australia and supported the New South Wales offer to hand over gun control to the Commonwealth.