The case prompted a Wolverhampton Crown Court judge to issue a public warning that this was the lowest sentence people could expect if found in possession of such a weapon.
Steven Morton claimed not to have know this when he bought three through a Chinese website, Wolverhampton Crown Court was told.
Each was disguised as a torch, complete with a light that could be switched on and off.
The second batch, which contained two of them, was intercepted at a Royal Mail sorting office in London on February 2, disclosed Mr Peter McCartney, prosecuting.
They were being sent to the Wolverhampton home of the mother of 49-year-old Morton but he immediately admitted ordering the weapons when contacted by police the following day.
He also revealed that he had already received one from the same source - the Wish website, the court heard.
Mr McCartney continued: "The defendant said that he had not known they were illegal. He said he was fascinated by them and that was why he had placed the order."
Mr Niall Skinner, defending, said: "He has not been in trouble since his 20s and his last conviction was 22 years ago. A lesson has been learnt about buying goods on the internet.
"He had no intention of committing any offence and has been entirely honest with the police.
"He even volunteered the fact that he had already received one of the weapons but nothing I can say can make his situation any better.
"I cannot claim exceptional circumstances and there is no latitude for the normal credit for an early guilty plea because it is not applicable with this offence."
Morton, from Clifton Street, Sedgley pleaded guilty to possession of a prohibited weapon and purchasing prohibited weapons.
He was sent to prison by Recorder Simon Ward who told him: "You have been very realistic about your situation. After the police discovered you had ordered two disguised stun guns you co-operated fully.
"I accept that you are extremely sorry and embarrassed by the situation you find yourself in.
"Stun guns are extremely dangerous pieces of equipment and that is why Parliament has said that people who possess them go to prison for at least five years.
"A message must go out that this is the case even if you do not take the weapon out and threaten someone with it.
"You told police that your partner often worked late and it could be useful if you gave one of the weapons to her. If you had done that she would also have been looking at five years in prison."