Hello @ I Creep Around
In general, when looking at multiple versions of the exact same GPU (for example that GTX 970) you notice that price differences coincide with the fact that there are quite a few different manufacturers offing their "version" of that hardware. In some cases, the differences are minor, but noticeable (for example the ASUS version may have a higher MHZ rate, meaning it will run faster slightly, that say the ZOTAC version), whilst all other stats remain near the same..
These manufacturers difference do stem from the quality of components they use; so in essence when you see a negligible price difference, it is more than likely due to overall cost of components.. Now does this mean the cards are REALLY all that different? To a degree, however, more than anything it is that some components are of BETTER quality than others and so some manufacturers are more noted for their quality than others. So which is which? Obviously you can go with a type you know and trust (if you have such a brand you become familiar with) or, go with actual test market reviews (as opposed to users reviews, which tend to be more biased and emotionally driven.)
In the end, (and of coarse this can be always argued) current trends place ASUS and EVGA as some of the best manufacturers currently.. ( just to give you 2 top examples). But in the end, if you are concerned with budget as well as quality, go with the info you do trust before making any decisions.
Hope this helps.