yo down here in Austin, TX, as I suspect with anywhere else, it all depends on who you buy from and who you run with. It doesn't matter which sub-cultures you buy from because usually (except the Skinheads, but i'd never do business with those assholes) each sub-culture employs any number of different races, and different races have different dope.
If you buy from the Hispanics, which almost everybody does, you're almost guarunteed to get pretty crappy Tar. Once in a blue moon you'll get some powder from them though; You're more likely to get the powder from the South/Central Americans (sorry I just don't want to list every ethnicity), but it's harder to find a South/Central American hookup. The powder you get from either of them is brown to off white stuff, and it's usually very good.
If you buy from White people you usually get whatever the Mexicans have, because usually they just buy from them. But sometimes(more frequently than with the Mexicans, still rare though) you will get some Powder. This Powder varies in color from Brown to White, and it's probably the worst Powder you can get in this city. That might sound bad, but it's better than all the tar we get here, and some Tar's actually pretty good. I have no idea where they might get it from, but if I had to guess; I'd guess they get it shipped from a friend in another part of the country where powder is more prominent.
If you can find an Asian hookup(which are pretty rare) you are almost guarunteed the best powder in the state. This stuff is very pure and is always white.
When you buy from people like this, that sell to dealers, you buy in ounces, and the dope is almost always in a single plastic bag; never pre-packaged. But when you buy from a hookup, or from a street dealer it really varies. It seems like the most prominent form of packaging in Austin, and most of texas is foil, squares of plastic cut from garbage/plastic bags, or balloons. But sometimes you get it in little plastic bags or magazine paper wraps. Some dealers(I've never seen anyone besides me do this, haha), who love stamp bags so much, spend the time to package their dope in stamp bags with their own stamps.