Yes, it's much too expensive for a "building" copy, which is why that kit is best suited as a collector's kit, one to proudly show off to your modeling friends, unbuilt. All those early Revell type "S" space, rocket, and missle kits are very, very pricey, especially in such great condition. They are rare and hugely collectible and have been so for more than a decade and a half now--which explains the seller's $99.00 reserve. These kits just don't come around that often. I should know, I've been collecting them (all brands) for 20 years now and still have many holes in my "want list." (I'm cursed with being both a builder and a collector.)
Even missing just one part, that Moon Ship is a steal at that price, assuming the bids don't "take off" (yuck, yuck) during the last moments of the auction. The Sixth Edition (1994), which I just checked, of the Collector's Value Guide for Scale Model Plastic Kits (commonly referred to as The Burns Kit Guide) has it listed as "$150 and up." That's eleven years ago! By now, I'm certain the current edition would have it at double that now. I've only seen one other copy of this Moon Ship in the same condition from vendor at the IPMS National con in Albuquerque, 10 years ago.
BTW, kits from that era, especially those from Aurora, were frequently missing parts because of the sometimes careless, assembly line manhandling they received at the factory. Parts commonly fell off the sprues. As a kid in the late 50s, I discovered this the hard way. So I always checked the parts list on the instruction sheet before leaving the hobby shop, just to make certain a kit was complete. Sometimes they werent, and it was back to the hobby shelf for another copy.
--Ken