Also to blame is the rise of smart phones. I've been doing flea markets for about 4-5 years now, and I will agree the finds seem to get worse. More and more I will see people selling small amounts of games, who used to just sell them cheap ,individually price them based on price charts or ebay because they can always look up a price on their phone.
Still I do find some decent gaming related stuff. Mostly ps1/ps2/wii stuff at the moment is really cheap. My best find of last year was picking up a bunch of ps2 shooters (shmups) for $1 each which I was pretty happy about. People seem to be nes/snes/n64 crazy at the moment. As far as turbo finds, I saw a keith courage once for $2 but passed because I already had it. I do see a few resellers with occasional turbo games but they don't count, and their prices are usually higher than ebay.