Bloemfontein - The alleged Mangaung plotters had planned to buy two big mortars, 10 smaller ones, dynamite, and a grenade, the Bloemfontein High Court heard on Thursday.
A State witness, known only as Mr B, testified that he saw these weapons the day before the alleged planned attack on the African National Congress's national elective conference in Mangaung in December 2012.
Judge Mojalefa Rampai was hearing evidence in the trial of Johan Prinsloo who faces charges of treason, conspiracy to take part in terrorist acts, and possession of illegal ammunition.
Mr B testified that he saw the ammunition on December 15, 2012 - a day before the planned attack - at a flat in Reigerpark, just outside Boksburg.
He said the big mortar bombs were on sale for R10 500 each or R21 000 for both.
Mr B testified that he then arranged with the sellers that Jaco Scherman - also a State witness and police informant - would come later in the day with the money to buy them.
He said Scherman, however, phoned him that afternoon to tell him the deal did not materialise.
Mr B said he told Prinsloo, who then asked him to continue trying to get weapons, but he had to cancel everything after he got a call from Scherman warning him that there were police officers at Prinsloo's house.
Prinsloo, Mark Trollip, Hein Boonzaaier, and Martin Keevy, were arrested in connection with an alleged plan to attack the ANC's conference in Mangaung.
Trollip pleaded guilty to a charge of conspiracy and was sentenced to eight years imprisonment last year.
Charges against Boonzaaier were dropped and Keevy was declared unfit to stand trial.
The trial was postponed to Wednesday, February 26.