Yup, prices of AK pattern rifles have increased, but hasn't everything else? Not to fling poo at anyone's parade, but I too believe it has much more to do with the political atmosphere than any grand epiphany that AKs are "better".
I've long believed that both the ARs and AKs are great weapons and anyone who relentlessly carries on and on how one is so vastly superior than yhe other for what they were designed for either has way too much time on they're hands or is a simpleton to sorts. They're both swell, don't over-think it.
I've noticed other rifles/carbine enjoying a boost in monetary value as well. The M1 carbines soared into the stratosphere when they began to dry up. The once under-appreciated SKS is basking in the sun as well, with even the Yugoslavian often going for over $300.
It's an atmosphere of uncertainty and perhaps fear, aided by a (often perceived) drying market that's driving these prices.