2019 MARKET UPDATE: BARELY CLINGING TO HOT STATUS
Just like most DC Comics characters, Flash is suffering as speculators pile in to more and more Marvel comics.
The lack of a consistent DC Cinematic Universe output is hurting back issues across the board.
The fact that my pick of CGC 6.0 appreciated 23 percent is a miracle if you compare to other DC issues on the list (and some which fell off it altogether).
If you're still on the fence and didn't buy one, then I hesitate to recommend that you do so now. Put the money elsewhere.
Here are recent sales.
2018 MARKET UPDATE: LOWER VOLUME, PRICES STABLE
In a flash, the fuss about Silver Age Flash comic books is dying down. This book was under-valued for years, and briefly red-hot.
Now we see prices softening a little, though at grades above FN it's still a very scarce book. The CGC 8.0 price is a big increase on the previous year.
2017 MARKET UPDATE:
Interest in Silver Age Flash comics has not slowed down. Some key issues, like 117 (first Captain Boomerang) came and went, as the reason for their temporary rise (movie) passed. Flash 123 shows no signs of slowing down.
This book is tough to find in grades above 6.0. There have been no sales in grades above 8.0 since our last report.
The renewed interest in many Flash comic books is mainly driven by the TV series, plus the crossover potential, as well as the upcoming DC movie releases which have the chance of featuring the Fastest Man Alive.
Flash #123 is special because it re-introduces the Golden Age Flash. The cover and story are considered by fans to be classics.
Other Flash books on the Hot 100 List:
Prices have risen dramatically, especially at grades above VG (which is about average for this book -- certainly most we are offered are beaters well-loved by their owners).
Aim for something nicer, ideally with OWW or White pages.
Note that there is very little data on super-high grades above 9.0, so proceed with caution before investing major money in a high-grade example (if you can find one!).