2018 MARKET UPDATE: THE ATOM'S PRICES GETTING SMALLER
There aren't many bright spots on the price horizon for this book, but it moves a little way up the list due to dire performance from others above it.
Some grades saw appreciation, but perhaps this book suffered from speculation -- Atom is one of the DC Universe characters that has yet to make a big screen appearance.
A movie treatment would spark a feeding frenzy on this book.
2017 MARKET UPDATE:
Another Silver Age DC key issue that is cooling off, mostly due to over-supply of low-grade copies and not much activity in the high end of the market.
The exception is a very nice CGC 9.0 sale. We feel this book is drastically under-valued in high grade... Try to find another so nice.
The entire run of Showcase (with the exception of some very random non-hero stuff) has been heating up, with these early Silver Age books containing plenty of key appearances.
Also on the Hot 100:
Several of the series appears on our Hot 100 list, and while many of them have already become quite expensive, the first Silver Age Atom appearance seems under-priced at the moment.
It's a pretty tough book to find in higher grade, but be patient and the right book will come along in time.