00 expedition replacing key fobs?

i picked up a 2000 expedition. it didnt come with the power lock key fobs. i guess they were somehow lost. how do i replace theses? it it easy to program aftermarket ones without having the originals or do i need to go to the dealer? any idea cost? thanks

The aftermarket key fobs will work. They are easily programmed. Just have the fobs with you and turn the ignition to the run position 8 times. Hit either the lock or unlock button. If it works, it is programmed.

awesome..i actually found new factory fobs online for 20 bucks. just ordered it :) thanks for your reply

This a great site for most key fob programing and it's free.
http://programyourremote.com