The Magpies, who were relegated from the Premier League last season, have yet to pick up a point in the second tier after losing 1-0 to Fulham and 2-1 to Huddersfield Town.
Benitez told Sky Sports News: "We know what we need. We knew what we needed and now it's just a confirmation that we need that. So the question is can you get the player you want?
"When the Premier League clubs have some money it makes it more difficult because they can spend more money and you can see the prices of the players. It's not realistic but it's what you have.
"So we have to make sure we sign the players that we need. It's not important the name now, it's just that we're sure they can do the job."
Newcastle face Reading in their third Championship game of the season on Wednesday night