Can somebody please explain me how many watts a Radeon R9 (an example) is used when mining vertcoins? I want to know if it's a good choice to buy a graphic card, instead of buying an ASIC to mine SHA256/scrypt. I'm newbie in this one.

A computer usually consumes ~300W, right? And adding a powerful graphic card, wouldn't that make me waste more with electricity bill, than profiting mining it? I pay around $0.20 where I live, by the way.

Thanks in advance!