Mirage 460's for $100 - good deal?

Good speakers that blast well and resist the urge to be labeled audiophile. If you're looking for detailed soundstages with nuanced sonic layers, the MIrages just aren't built or designed for that. BUt if you want a good sounding pair of garage or background rock speakers, then there are quite good, especially for $100

I just picked up the 460’s an older Harmon cordon reciever energy sub two Yamaha surrounds and a paradigm centre for $80.00 Canadian dude wanted  150. The 460’s sound great the energy sub is great also I added this to my existing energy centre,Yamaha rxv359 an a couple cheap legacy ls 4000 surrounds end result a system that will get you in trouble. 

I owned a pair of 760s (next step up from the 460) for a couple of years back in the early 90s. They were a good speaker, but I am not sure how they compare with what you have as I have never heard the M12. The 760 sold for about $1000 back then and I believe the 460 was about $700. If they are in good shape, I would say they are worth a try at that price. That will be the only way you will know if you like them better. If not, you should be able to get the $100 back out of them.