A 1975 X-Men comic book fetched an impressive $170,000 at an auction ... marking it as the second-highest price ever paid for a '70s comic book.

ComicConnect recently sealed the deal on "Giant-Size X-Men #1," the only comic to ever score a near-perfect 9.9 from CGC.

The site's President, Vincent Zurzolo, noted that '70s comics often linger in discount bins for years before nostalgia and significance catch up -- and bump up their value.

Case in point -- highly-graded copies of "Giant-Size X-Men #1" were selling for $350 in '95 ... and by '99, they had jumped to $575.

The pandemic bumped prices even higher -- with the OG investment of 50 cents morphing into the recent 6-figure return. In other words, people were bored out of their minds!

Zurzolo explains the buyer, a seasoned pro at collecting comics from the 1940s to the 1960s, snagged this gem as part of his investment strategy.

The only other '70s comic to sell at a higher price is "Marvel Spotlight #5" -- notable as where the character Ghost Rider makes his first appearance -- sold for $360,000 in Jan 2024.