French national Olivia Godefroy said Armand Pacombe Djedje agreed to pay her the cash to wed Devine Atalako Abanda in Winchester in February last year.
She said it was so the Cameroonian national could get papers to live in the UK.
Under cross-examination she denied she had been in a relationship with him.
Ms Godefroy, 22, of Grove Street, London, also told Winchester Crown Court she had not suggested the pair get married.
Mr Abanda, 27, Mr Djedje, 30, from the Ivory Coast, and 31-year-old Belgian national Olivier Attie each deny one count of conspiracy to facilitate the commission of a breach of UK immigration law by a non-EU person.
The ceremony at Winchester Register Office on 28 February 2014 was interrupted by immigration officers.
Mr Abanda, of Hillards Road, Uxbridge, west London, had tried to marry as his visa was due to expire, the court has previously heard.
Prosecuting barrister Michael Butt had told the jury Ms Godefroy was a bigamist who had been married twice before, with her last marriage taking place weeks earlier.
Mr Djedje, of Evelyn Street, Deptford, south-east London, and Mr Attie, of Guibal Road, Lee, south-east London, organised the marriage, the court has heard.
Jurors have already been told a number of documents were found in baggage belonging to the wedding party, including a "crib sheet" giving the bride essential details about her prospective husband.
The trial continues.
A bride who has admitted being involved in an alleged sham wedding has told a court she was due to be paid £2,000 to marry the groom.