terry.330's post above said it all. I've been saying for at least 5+ years that it doesn't make sense to even bother getting into AES given the prices and the fakes. That is starting to be true for MVS now as well as for many other systems.
As for good deals "back in the day", man, I don't know how many people here remember cosmicco and "Queenie". She would send inventory lists in the late 90s and early 2000s with, I don't know, 32 copies of Pulstar MVS for $26 each. She had everything and EVERYTHING was cheap (except for new games). Then you had Shinichirou, who sold BTG Jpn AES for $200 all day long. Anyone else remember SNK USA blowing out their last remaining stock of Metal Slug X US AES for $199 and Last Blade 1 for $149? Hard to believe, but its true, and most of the stock sat there forever.
When you remember things like that it makes it impossible to pay today's rates for anything. Which means you probably won't be adding much to your collection, hopefully you got the big stuff out of the way already