Not likely, but maybe I'll be wrong. Those with an "extra" $350k (and those guys are just all over the place) wouldn't likely put it somewhere where there's no return on profit. There's a real good chance those same folks have to SELL something to get liquid. After all that's what we're talking about here - sunk cash for something that won't (in that collector's lifetime) be converted back to cash. Highly unlikely. Even the Steve Geppi's of our hobby prefer to MAKE money on our hobby vs. SINKING it forever.
A breakup is much more likely (see Mark McDermott entry in the encylopedia). Even with prices all out there and there never being any conservative forces or potential price retreats this book will top at $200k, probably less. Most folks don't have raw cash at that level and Mastro ain't taking credit cards or promises (not to mention CGC trade). Even fewer folks are willing to trick their bank into a a fresh mortgage just to pull out cash and speculate on the break value.
If you've a house with $200k to pull out of it - would you? To buy some Spidey pages, nice as they are? More importantly, would you still be married the next day? All the real players at this level, that give a [embarrassing lack of self control] about funnybook art, are thinking these same thoughts and all but two will walk away. The two that remain will determine the auction price, but not more than $200k.
I'm not looking to join the lousy naysayers group, but having myself offered some supposedly top stuff over the years (@ the 10k+ level) has taught me how much hot air there is in this hobby. Any of you that haven't played there would be amazed how few are standing after you mention a "real" cash (vs. cash/trade or all trade) on-the-spot price. The hobby pyramid narrows dramatically as to number of players once you cross the $2000/$2500 mark for immediate cash no time payments. Another tier is crossing $5k, where 50-75% of remaining players drop off, crossing $10k means talking to under 10 people. There's a long stretch from $10k to $200k (or whatever).
As always "cash is king" because it offers unlimited opportunity, all other methods are "problematic" due to inherent limitations and so full of "apparent value" bs. Even time payments and credit lines bear hidden (for either the buyer or seller, or both) "time value of money" constraints to be factored in. No special math needed for straight cash on-the-spot.
But I could be alllll wrong!