The former Huddersfield man has been outstanding for Rangers this season and his form will have caught the eye of other clubs.
The Hoops will be keen to resist offers in the summer and Bidwell knows that Smithies is priceless as far as the club is concerned.
He said: “It's hard to put a price on it. With the amount of penalty saves and points he's won us this season.
“You can't put a price on it. He's experienced now as well. It's not just what he does on the field, it's what he does off it.”
Smithies is set to sweep the board at the end of season awards and Bidwell admitted seeing him sign a new contract, keeping him at Loftus Road until 2020, was a huge morale boost to the squad.
“I think he's been our player of the season by far and for the club to sign him on a new deal is great for the club and for the team. If we can keep the likes of Al here, we can be a bit more of a success,” Bidwell added.
“You're playing in a team and you don't want to lose your best players and Al has been a massive part of this season so moving forward it can only be a good thing.”