Sorry everyone, I appreciate all of your advice and feel pretty bad not replying sooner, especially on a post where I'm asking prompt advice. I read all your advice last night, then approached the seller.
To be clear and answer some of the questions above, I've paid, and I'm out just under $70 so far. Of course, all that's tied to this transaction, so my money is safe.
If this person were local to me, I'd be 100% willing to cough up the extra $80ish if they would allow a local pickup. The frameset and misc parts is totally worth it. However, another $80ish + sight unseen sale and crappy pics + unknown shipping costs + holiday shipping risks?
Not so much, at least not for me. Although if the seller will do local pickup, I see value in any BF'er that's local who wanted this at $150 a shot at it, understanding the risk involved.
I told the seller last night I'm going to reach out to eBay to see what they recommend from the buyer's perspective. Will be doing that tomorrow around lunchtime, with intent to wrap up a decision on this by EOD tomorrow. To DD's point, this already left a sour taste in my mouth, and I don't want it looming overhead during the holidays.
FWIW, the seller has less than 140 feedback so not really "seasoned" in my book. They have a believable (albeit somewhat lame) excuse on how this happened: They created this using the new auction-with-best-offer format eBay started this past year or two. The seller set a rejection price on the buy-it-now portion to $150 and claims they thought this would force the auction reserve to be $150 and were "shocked/pissed when it closed below the threshold set"
I did a full search on the seller's closed sales. This one is the only one that shows up, so I guess it's been at least 6 months since they last sold anything.