I would highly recommend GPU alt currency mining. My rig costs 2k and gets 0.15 BTC per day (ish), so it seems pretty good. Also, unlike ASICS, GPUs and mobos and such actually have resale value because they are multipurpose. Check out coinminingrigs.com for more info.
0.15 BTC * 30 days = 4.5BTC per month
Assuming $100 per BTC, that's $450 per month
I don't know what your electric cost is, but I can't imagine it being lower than $50 for such a rig, so profit is about $400 a month
$2,000 / $400 = 5 months until you just pay off your rig and start earning some money.
If this alt-coin difficulty goes up by 25% to 50%, that's another 1 to 2 months to wait.
If the value of the altcoin goes up by some percent, then it's a toss-up between paying off your rig and start making a profit earlier, or making a profit right away by having bought $2,000 worth of this currency directly, instead of mining it.
For example, if this alt currency goes up 10% every month, you'll pay off your rig in 4 months, and have a ~$600 profit at the end of month 5.
If you had just bought $2,000 of that currency directly, at the end of 5 months it would have been worth ~$930, meaning you would have made $300 more just by buying instead of mining.
Point is, this whole thing takes a lot of guessing, research, and planning. Plus, Bitcoin value continued to grow considerably over the last two years, due to actual adoption by the market, and thus the profits still stayed up despite more and more miners adding their hashing power. I just can't see alt coins growing is value for very long, since they don't offer any benefits over what Bitcoin provides (i.e. I only expect them to grow due to miner adoption, not the economy as a whole), while at the same time there is A LOT of freed up GPU power moving into it from Bitcoin miners that were replaced by ASICs. So, I think investing in an alt-coin miner is extremely risky right now, because I don't believe it will stay profitable for very long.