Avenger II is a bit more compact, combines linear & TIR optics, and has multi-color options.
Price depends on a few things....is the cig plug cut, does it come with all mounting hardware, how much was it used, date of manufacture, condition, etc.
IMHO, $150 used sounds a little high, since they’re discontinued and pushing for the Avenger II now. IMO, $150 would be more suited for new one, and $125ish would be more appropriate for a used one in like-new condition (little use, full wiring and brackets, etc), but that’s just my opinion. On the other hand, if you’re selling on eBay, you can ask for it and sees who bites b/c I’m sure someone out there might pay more, but buyers here are much more informed about fair asking prices for new & used prices