Don't have a door key for my car, need to get one made...?

I just got a used car a couple weeks ago but didn't get a door key when I bought it (just the remote opener). It's a late 90s Thunderbird and I was wondering if anyone knows how much it will cost to get a locksmith to make a key for it. I am able to take the car to the locksmith so they don't need to come to my house. Thanks!