There is very little to distinguish between various graphics card manufacturers these days. The only real difference are cooling solutions, RAM, games bundles and overclocking ability.
If you go for a no-name brand chances are they will use cheaper memory that wont overclock well at all and they wont bundle much software with the card. The card will still have to work and the correct speeds and it will probably be just as reliable as any other card (its not in the manufacturers interest to make a card that breaks as they are obliged to replace it).
The only thing that I do warn you about with cheap or unknown cards is that their technical support will probably be crap, which will be a nightmare if you do have a problem.