Try to stick to whole foods for protein sources (lean meats like chicken, etc). Protein powders help to get in the extra protein after workouts and when you don't have time to make a meal. I would recommend Optimum Nutrition's 100% Whey as it is very cheap ($25 for 5lbs) and tastes good. Try any of the flavors except cookies and cream (its nasty).

In general I would say avoid the protein bars, most of them are junk and not much better than eating a candy bar.