I currently have an HTS2500 that I picked up several years ago for $100 and I have an opportunity to get a NIB AVS2000 for a great price. But I agree Monster retail prices are crazy
!! But on the pre-owned market you can find some pretty good deals. As for needing one I don't really know but I will say that in my area we have lots of brown outs and such especially in the summer months. As for voltage fluxuation's I don't know for sure.