I think wine is a lot like being introduced to music. You start out with what's on the radio and consumed by the masses. This would be stuff like the Australia's Lindemans, California's Ernest and Julio Gallo, Chili's Santa Carolina, Italy's Masi, etc. The average section of your liqueur store is going to stock only the 2 or 3 most popular wineries from each producing country in large quantities.
But there's a reason why they're so popular. They are sold "ready to drink" and require no additional aging by the customer. They're inexpensive, produced in huge quantities every year for each varietal, and are available everywhere. And to be honest, these mainstream wines aren't half bad.
I'd stick with these popular, widely available, and inexpensive wineries until you get to know them - sampling various types and varietals of wine made by each, at least until you know what types of wine you enjoy most. For reds, do you enjoy a palate of fresh berry with hints of vanilla, or do you prefer earthy tones with notes of cinnamon? Even this is a ridiculous oversimplification, because wine is about the most variable and complex "food" you'll ever test with your senses.
I agree with others here about visiting wineries and wine tastings. Even take advantage of free promotional wine tastings at your local wine store. We used to organize a "wine night" once a week, where each of us would take turns hosting a party where everyone was expected to bring a bottle of wine to. All the wine goes on a table, and everything is opened at once to allow people to choose what they want.
Once you know exactly what you like, let the staff know while you visit a much larger wine store and they'll usually be of great help in expanding your wine "horizon". To a certain degree, price does make a difference generally speaking. Just keep in mind that the $8 bottle of wine is meant to be drunk right away, while more expensive wines may not be. In fact, the higher the price, the more chance there is that the bottle of wine you buy might need (or at least benefit from) additional aging.