What is the cheapest way to make my 2002 Ford Taurus adaptable to an aux port?

My car doesn't have an external cd unit. Would I have to restore in buying an aftermarket stereo adapter panel and then buy a stereo for it or is there just an option of getting a cable to fit in the existing panel somehow?

Cheapest and easiest would be to install an aftermarket unit with that capability.

I'd certainly get an aftermarket unit with an aux port.

Example my unit DEH-150MP cost $50, plus a wiring harness $10.
The wiring harness is not even necessary but it does make things easier and more neat inside.

An adapter such as Scosche FM-MOD02 would work for $30 in a pinch but sound quality won't be as good as it could be. Scoshe is not exactly known for their quality and this is the cheapest looking one out there. Plus it will take just as long to open up the dash and install this one opposed to a shiny new deck with added features. There's a reason hardly anyone uses these type adapters.