Technically it's still illegal, torrent or not. I would still say you should buy it, it's not going to be expensive. I'm a very cheap person myself (75% of my games on Steam are free) but sometimes, it's better to pay.
If you don't have a credit card, (if you are under 18 or whatever the requirement is in your country) ask a parent or friend to buy it (if using Steam or a similar service) or just go get a copy from the local game shop.
Sorry but it's the best way. And the most legal.