Resale value of a ASIC is extremely low considering it can be used for nothing else. And when you intend to sell it, it will probably won't be worth while for someone else to purchase.
Are you talking about sha256 ASIC?
http://www.alloscomp.com/bitcoin/calculatorYes. Thats a great bitcoin tool, but I know with only 30-50 gh/s bitcoin wouldnt be all that profitable.
I could be wrong, but aren't there a few sha256 alt-currencies out there? I know they're value is really low right now, but would any of them be worth mining with the hope that their value could go up?
They quickly get squashed to death by sha256 ASICs the moment they become more valuable than direct BTC mining. That's what scrypt avoids in the first place.
If you intend to mine those now, that's a mix of mining and speculating. Perhaps get BTC out of the GPUs, and buy whatever alt-coins you like, including those sha2