Going forward, I believe the only steels that will command very high prices in future will be the Asian steels with nice slipcovers. They have built in rarity value right from the get-go (many are hard to get even before they're released) and aren't likely to be re-issued.
Many guys new to steelbooks don't really get the appeal of them, but seasoned collectors tend to prize them very highly, hence the high eBay prices. Releases like the Taiwanese Amazing Spider-Man and Korean Snow White & the Huntsman are far more likely to become future grails than anything coming out of Europe, Canada or the US.