I am basing it off caraudio.com sales prices - which I watch on a regular basis for the trade-in program.
http://www.caraudio.com/forum/showthread.p...light=SAX-100.2
200/185
http://www.caraudio.com/forum/showthread.p...light=SAX-100.2
165
http://www.caraudio.com/forum/showthread.p...light=SAX-100.2
200
http://www.caraudio.com/forum/showthread.p...t=Sundown+100.2
175
http://www.caraudio.com/forum/showthread.p...t=Sundown+100.2
150
An average figure seems to be 175 to me I sell good condition used 100.2s for ~200 when I have them.
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As for the 1500D I was agreeing with James that 325-350 was a reasonable used price and seems to be the average. A mint condition 1500 with new casing can fetch 375-400 on occasion, though,