If you are 17 or older, two types of emergency contraception, Plan B One-Step and Next Choice, are available directly from a Planned Parenthood health center or from your local drugstore. If you are younger than 17, you'll need to go to a health center or private health care provider for a prescription.
Ella and the copper IUD are not available over-the-counter. If you are interested in either of those options, you'll need to talk to your healthcare provider.
Costs for emergency contraception range from $35 to $80 for pills, to several hundred dollars or more for the copper IUD. Insurance may (or may not) cover some of the cost of emergency contraception in some situations.