Help! Tie Rod Problems and Cost?

Hi everyone. I started hearing a loud revving noise in the front of my car (96 Tbird) a little over a month ago which I thought was my engine at first. But then I realized that when I turned the steering wheel a certain way, that the loud noise would stop until it went straight again. I was told that it sounds like a tie rod problem and that my wheel could come flying off at any speed. This was after I got a flat tire about 4 days ago with my 3 yr old daughter in the car and I'm now driving on a donut! Now I am really freaked out to drive anywhere at all! I have a few questions that I hope someone can help me with. The first one is, how long after this starts happening does it usually take for something horrible to happen? Does this sound like a tie rod problem for sure, or could it be something else? Also, how much will it cost for me to get this fixed approximately, and is it even safe for me to drive to the mechanic? Please help! I am so nervous about this! :( Thanks in advance to anyone who can tell me anything you think I should know! I really appreciate it!

A "revving" noise does seem like it would be engine/drivetrain related.
It could be many things.
Maybe it's just a worn accessory belt, idler pulley or drive belt tensioner.
If it is worn tie rods and/or ball joints, they can give out at any time.
Meaning the wheel/tire assembly could come off.
My best advice is to take it to a reputable mechanic.
Oh, please don't drive on the spare (donut) tire very long.
They are designed just to get you to a repair shop.

And if you need to drive with a donut, put it on the rear, never on the front.

Thanks guys! I got it fixed and it ended up being a Hub Bearing. I'm so glad its fixed now!