Recently, my speedometer hasn't been working right. It either shows the correct speed or stays at 0. I noticed something in another thread that if the speed sensor went bad, the check engine light should go on, but mine hasn't gone on. I took it to the local car shop for an estimate and they told me the sensor and cluster both went bad and repair would be about $400 with labor. I'd rather not spend the $400 and see if I can buy the parts and do it myself.

What should I do first and where should I buy the parts?

Thanks,
Chris