I would guess that most of these people are buying them as an investment, as modelers usually have other means of acquiring great deals other than fishing in the Bay (i.e. friends, older club members, that little LHS in the next town over, flea markets, etc...).
I dunno, maybe it's just me, but I refuse to pay more than 50% of an items original selling price for excellent condition used engines, and no more than the original selling price for NIB models (excluding way cool, gotta have vintage engines). I don't care how "rare" an engine is, or is becoming, I'm not going to pay an arm and a leg for it because it might not be around in a couple of years. I'm not saying that I don't shop the Bay - through patience I've gotten some fantastic deals there - like the $.99 NIB Fox .40 RC!
Everybody has a price that they're willing to pay, and because I'm one frugal SOB (and darn proud of it), I'm ensuring that there'll be a lot of engines in the Bay to go around. You all are welcome.
For the most part though, I'm with DD - get 'em while you can. However.... there's an interesting trend going on in the electric plane groups - I'm seeing more and more "Electric to Glow" posts popping up, and there's even a RC heli pilot at work who was a die-hard E-guy six months ago, but now he's flying a glow again and is poo-pooing electric. Could it be just a fad? Are the
real RC pilots going to hang in there long enough to kill the E-fad? [X(]
-Joe