As far as why this particular kit is drawing big bids, it has to be on the perceived rarity of the original hang tag packaging (along with the P.T. Barnum factor.

).
Since Big Berthas are readily available at just about any rocket shop in the nation, and I don't think there's much danger Estes is gonna delete it from the lineup (I'd guess it's probably still among their top 6-8 sellers), there really isn't much "rarity" to the kit itself. Plus I bet about 90 percent of all serious rocketeers could scratch-build a Bertha from the raw parts in about 45 minutes tops from sheer memory.
It's quick and a snap to build, you can finish it however you like and if you take reasonable care, it comes out looking good. It is great for classes and demos because it is so big, flies low and slow, and allows everyone to see what exactly does happen to a rocket in flight.
I built my first Bertha in 1968, and flew it for about three years, until the nose cone and body tube snapped back into each other too many times. Too many bites out of the balsa cone, and dents in the body tube... blah. Sometime in some basement cleaning, it got crunched, and that was the end of that.
Now, I've got a brand new edition of the Bertha Family ... Baby, Big and Bigger... down in the basement. All built up, gloss black and silver cones, ready to rip.
Gonna whip up some custom decals to stick on 'em. Why not?? LOL.
I suppose the next steps would be a Mini-Bertha (13mm BT-5 motor mount in a BT-55 body, about 15" long), a Micro-Bertha (MMX motor mount in a BT-20 body, about 10"). ..
