Steel has also, much to some people's surprise, become fashionable again - see my comment above about steel singlespeeds.
In a few years, after it's been semi forgotten a bit, no doubt the "industry" will be trying to big up aluminium again, as a newly discovered wonder material that is so "this year".
I picked up an old 90s Tange frame the other week for £30 - it seems sound.
And worth bearing in mind that some of those steel 1 inch threaded headsets fitted in some of those old frames are pretty bomb proof.