Yeah, that was the intent of my question. If you could in theory buy some mining hardware today and have it delivered in one week or less, what would 1GH/s be worth right now.
It seems I wasn't too far off with my $100 figure, you would probably break even at the very least. $75 should ensure some profit.
Just goes to show I paid about 3x what I should have for a couple of USB Erputers. Oh well, live and learn. At least I didn't buy 10 or more.
Who knows, maybe difficulty won't keep skyrocketing if all the promised ASIC deliveries don't come to pass and/or the BTC price keeps dropping. BTC losing more value would obviously negatively impact ROI though. I tend to think people who do get ASIC devices will mine with them no matter what though, since they can't do anything else with them. So the difficulty skyrocketing is virtually guaranteed, only an impediment to ASIC devices being delivered can prevent it.