NOS ones used to pop up once in a while on eBay, although the 7/8 ones seem really hard to find. The last two cars I had came to me with heater hose in place of the bushings. I just used the polyurethane ones (black) because they have the shoulders on them and won't slide out.
There's an old thread which might be helpful.
http://forums.maxperformanceinc.com/...d.php?t=814904