The Manchester City striker is currently on loan at White Hart Lane until the end of the season, but his three goals in three games have earned him the attention of Redknapp.
"If he keeps going like he's going I'd love to keep him around. He's been excellent so far," said the Spurs boss.
"But the wages will be the problem because he's not cheap."
The North London club next take on Shamrock Rovers at home in a Europa League group fixture on Thursday.