The question is, what kind of confidence do you have in bitcoin? If you think it will flop, there's probably not much of a reason to invest any of your money - either in mining or in bitcoins.
If you think it might take off, you have three options (maybe 2.5). Mining with ASICs might be the way to go, but then you'll have to take on a lot more risk: will company "A" manage to get their ASICs on the market on time? Will company "B" ship them at all? If you invest in shares of a miner, will the operator be honest with you? Due to such a high demand, the value of ASIC miners is inherently tied to the value of bitcoin - if BTC is more expensive, so are the miners. This makes investing this route even more risky.
I would argue a safer bet at this point would be investing in bitcoins, since there are fewer risks (or variables) involved right now.
The third option, if you really want to play with hardware, would be to go buy a decent AMD GPU and get that mining for a few weeks. When it doesn't look like it's making much money for you anymore (i.e., when the ASICs kill mining for all lesser forms of hardware), you can recover most of your money by selling it.
My advice: if you wouldn't throw your $500 around at a casino, you probably shouldn't put it into BTC right now. Things will be changing a lot over the next few months. If it feels to risky, reevaluate bitcoin later.
Assuming the value were to stay stable. I was interested in getting the hardware, but I'm worried and ASIC company might do everything right and have enough supply for everyone that wants one, and it will make my hardware effectively useless profitibility wise. That is why I was thinking may spend $300-400 on a basic ASIC system, taking the rest, and then spend the rest on actual hardware.