In the "for what it's worth" category, I installed a commonly available ten disk changer in my T wagon a couple of years ago. The make escapes me at the moment, but it cost me $150 and, of course, connects via the FM antenna connector. I too was pursuing a directly connected unit with no success (way too big $$$). This one has been performing flawlessly and gives me four more discs and a wired remote to boot. The only problem you might encounter, and I don't know if it's a factor on the S/V series cars, is that it won't work with radios having dual antenna connections.

Good luck