Rangers have had two six-figure offers for St Johnstone forward Michael O'Halloran rejected by the Perth club.
It is unclear if the Scottish Championship leaders will increase their bid again for the 25-year-old.
O'Halloran, who joined Saints in 2014 after leaving Bolton Wanderers, won the Premiership player of the month award for November.
"The players we bring in have to represent value for the club," said Rangers manager Mark Warburton.
"We think we know what is good value. Other people might disagree, but that's our figure.
"It's got to work for the selling club too but we are comfortable our judgement is good."
The Scotland Under-21 cap has made 23 appearances this season for the Saints and scored four goals.
He played for Celtic as a youth before joining Bolton and was loaned to Sheffield United, Carlisle United and Tranmere Rovers before switching to McDiarmid Park.
Meanwhile, Warburton says there "hasn't been any contact" from clubs regarding Martyn Waghorn, following reported interest from English clubs in the 25-goal striker.
"If we get it right then players will want to stay, simple as that," said Warburton. "If a player does want to leave then they will leave on our terms."
Warburton says Rangers are "very close" to a agreeing a new contract with winger Barrie McKay.
And Ibrox midfielder Tom Walsh has been loaned to Dumbarton for the rest of the season.