I don't quite understand this argument. I think it's safe to say that anyone spending hundreds to thousands of dollars on a comic is of the "comic book collector" variety, regardless of what the issue or title is, whether Modern Age or Silver or Golden. But collectors ARE spending thousands of dollars on certain issues and titles. I don't think you can so easily dismiss WD as another Magnus 0. If anything, it's becoming a cultural phenomenon more along the lines of TMNT. The question is staying power with those collectors.
When TMNT caught fire in the mid-80s, did the collector community have these same arguments? If so, here we are 25+ years later, and people are still spending thousands on that first issue. It's become THE key of that era (whatever era that is...the 80s generation era?). Is Walking Dead becoming THE key of this current era? If not already, it certainly seems on the verge of it. So, I can definitely see WD Issue 1 becoming THE key issue for all serious collectors to obtain for years/decades to come. It's no longer just hype. There's something more cultural behind the frenzy, unlike those Valiant days of yesteryear that came and went so quickly.
The show's casual viewers are likely reading the trades. Whereas the hardcore viewers might be jumping on the floppy bandwagon (thus the inexplicable price jumps for the Weekly reprints). But the collectors are the ones laying down the big money.
Do I think these prices will hold up? Every instinct agrees with you actually. No way these prices remain this high. But I'm just not so sure this is your typical bubble. I don't see prices coming down to less than $500 for Issue 1. Sure, supply is certainly MUCH bigger than TMNT 1. But the demand could very well become a permanent staple of this era.
The trend is your friend....until the curve at the end.
Expect TWD to fall as Pre-Unity Valiants did.