Showcase #4 reintroduced the Flash to a new generation of readers and is considered by many to be the start of the Silver Age of Comics.

Showcase #4 1st Silver Age Flash For Sale and Current Prices

Showcase #4 has held it’s value over the years, but has recently been overshadowed by the Marvel stable of characters, especially with Amazing Fantasy #15 hitting the $1 million mark. If DC were to capitalize on this character we may very well see a resurgence in value.