I think that modern ones are in a massive bubble unless you can identify the rare few that are completely under the radar that will become sought after in the future.
Back in the 40s and 50s, virtually all comic books were purchased in order to be read, which is why those books are scarce and collectible.
Even in the 80s you had quite a few people buying comic books to read. Over the last 30 years, though, the vast majority of comic books sold were immediately bagged and boarded as collectibles. Long term, the demand is not going to be there for those books. The only thing driving prices up on modern books is speculation. That bubble will eventually pop.
There aren't many comic books published in the last 30 that I would pay more a dollar or two for raw. (Most I just wouldn't buy, period.)