Unfortunately there aren't a ton of good goalies available on the free agent market this year. In terms of fit, Martin Biron is currently playing backup on the rangers under the tutelage of Benoit Allaire. I can't imagine the transition from brother to brother would be one that is too difficult for him. He is a veteran keeper that the team desperately needs, but not exactly of the caliber most fans want.
Personally I really like Josh Harding. Injuries have really hurt his career, but hes got a phenomenal glove hand and almost baits shooters to taking a shot there. Given his natural agility and ability he may do quite well in Toronto if he can stay healthy. If he can't Reimer is also due for a better season next year, but I have my concerns about him as well.
In terms of who we can trade for, it's difficult to speculate. Schneider is seemingly more unlikely, Bernier would be nice but same old adage of young goalies in a rough market to develop and find yourself. It has been ages since the Leafs brought up an elite goalie through their own system.
"Many Leaf fans like to point to the 4 wins in the first 6 games and a sparkling 2.29 GAA as the promise Reimer had before a concussion derailed his season. In those almost 6 games Reimer posted a 0.912 save percentage, good by Leaf goaltending standards but hardly adequate league wide. Had he continued to play that way the entire season he would rank somewhere between 25-35th in goalies who have played more than 20 games in save percentage."
"His season completely derailed when he returned from injury - and finished with a .900svp - and a 3.10GA"