Any auto parts store. I would get an OEM replacement cable. You'll have to measure yours first, then you might do a little online research to find a shorter replacement. For example, when I do a search on rockauto.com, I get a different length TV cable for the 305 (47.5") and 350 (44"), and I can't imagine why they would be different. The one I'm using, a Pioneer CA-1970, is 43.75". I got it at AutoZone for $18. Be sure to get new seal too.