The Mundo Deportivo claims, which come from journalist Anna Cordovilla, are certainly good on detail.
But Sanchez Flores is now 3/10 to take on the role.
Elsewhere in Spain it had been reported this payment may not be necessary.
Former Watford manager Quique Sanchez Flores has also been linked this week but the Potters board will have to negotiate a fee with Spanish side Espanyol given that he is still under contract with them until summer 2019.
"I do not want to talk about me in such a big day for the club (Espanyol qualified for quarters of Cup)... you know I have been frustrated sometimes".More news: A swarm of armed drones attacked a Russian military base in Syria
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"I don't want to talk about me, but to enjoy these moments".
Martin O'Neill, the Republic of Ireland manager, is still regarded as an attractive option by chairman Peter Coates but Flores could make his return to English football next week.
But the 65-year-old said after the Republic lost their World Cup qualifying play-off the following month that he would need to have "a real think" about his future, and still nothing has been signed.
They had hoped to announce the hire on Friday but negotiations dragged on, meaning he is likely to watch Monday night's game with Manchester United from the stands rather than the touchline.
Niedzwiecki has been assisted by Under-18s boss Kevin Russell, who faced the media at a press conference on Thursday afternoon. They will be a lucky manager.