Well, if you already have 2 programmed keys, you can buy that off eBay and take it to a hardware store to have it cut and program it yourself. If you have one programmed key, you'll need to take it to a dealer and trade a lung for them to program it.
Keep looking around. I did end up getting two for about $20. Another search term to use is Ford Pats key.
My local dealer actually charges $20 for the key so in this case it'd actually cost you more. Programming was a half hour at $40 if you only have one key, otherwise the instructions for programming it are in the owner's manual.
Actually, be careful. On my 2000 Ford doesn't use the "PATS" system anymore. It's now the "Secure Lock II" or something like that. I think the term in is your owners manual. It's a slightly different technology, so you need to make sure you get the correct type of key. The keys for the Gen 3's are slightly different.
IIRC a new key bought and cut from the parts department is only about 25 bucks. You still program it yourself... more expensive to have them do it if you only have one working key, but if you have two keys, you can program it yourself and you just have the cost of the key.
Also FYI, I tried to buy mine online and I had it cut at Home Depot (in fact, someone in that section just did it for me for free) but as it turned out, the key was cut too far up the shaft and wouldn't turn in the lock normally. It ended up that you could pull the key slightly out away from the lock and it would turn, but it took me a little while to figure that out.. found out after I bought another key from the dealer. The dealer key worked perfect the first time though.
Good luck finding a hardware store to cut it; I had problems at both Home Depot and Lowes trying to get my keys cut; they have automatic machines there that cut the pre-programed keys for the people, so a lot of them don't do custom keys. I also had a problem finding an independent shop to cut it; many of them were worried that I would retaliate and charge them if they messed up a key (a serious problem when a key was worth 40 bucks.)
Also, depending on which year you have, you may only need one key. I'm able to program keys with only one key, but I believe later PATS systems required both.
I had the keys cut at a local key place for $2 a key. I went to one other place first and they didn't want to do it because they were worried they could screw up the key.
You kinda have to go by the picture of the key in the auction. Also most of them do state what years they'll work on. I think the ones on the 2000-2004 Taurus are Pats III keys.
At one point I did see someone who had them for $10 apiece and I managed to get two from them for $21 including shipping.
I was actually at a mall where they had a car key place as a sort of a stand alone booth in the parking lot. The guy there wanted $40 for a key and that didn't even include programming. Sometimes the dealer is cheaper or in fact, ebay is cheaper!
This past weekend I went back to the dealership to get two keys that they owed me for my new car (I always make them throw in a third key when I buy a car). The "Ford Trained Techinicians" managed to de-program my key for wifes car. I assume it's because they didn't take my key off the key ring when they did it, so now I have to call and b**** at the service manager because the dealership is about 45 minutes from my house. My good deal on the new car is looking a lot less good now that I have to go through this.