The flying Welshman is a target for several clubs across Europe but the huge price tag could be a problem for potential buyers.
Bale, 23, recently signed a contract extension until 2016 with Spurs. The Londoners would certainly demand £50m plus for the winger who can also play at left-back.
Real Madrid are currently without full-backs Alvaro Arbeloa, Marcelo Vieira and Fabio Coentrao who are all sidelined with injuries.
The Spanish champions signed Spurs playmaker Luka Modric during the summer transfer window and the White Hart Lane club could lose another star at the end of the season.
Spurs hope to keep their speedy Welshman but could be tempted to sell if a huge offer is made.