Don't forget to factor in difficulty doubling every 4 - 6 weeks - you'll probably find that you won't make back it's current BTC value. But, if you are paying for it with $ or €, it's probably still worth doing assuming that BTC continues to appreciate in value.

Just don't do what I did and bought a USB block erupter for 0.9BTC which has made me back 0.3BTC and now earns dust. I should have paid the $90 at the time and kept the 0.9 and I would have tripled my money.

If you think that BTC will continue to rise and it's easy for you to buy and sell BTC then just buy the BTC - it's less risky. If it's not so easy to buy and sell BTC then mining is an option albeit very risky.