Just like in the Project Runway retail challenges, budget has a real impact on design. If you plan to realize the project, it has to be doable.
Some things “do” easier than others. Matching chorus costumes, for example, typically need to be created from scratch and are, therefore, more expensive than pulling from existing costume stock.
Using existing costume stock is by far the best strategy for economizing. That is also going to be my strategy for Summer 2014. Thrifting is the next cheapest. (Actually, in theater there is sometimes the opportunity to borrow, which I don’t consider an option IRL.) Depending on the specifics of the item, purchasing at retail and building something from scratch are often comparable in price.
From 30 feet, a garment hacked together from pieces of thrifted garments will often suffice. Lately I’ve been thinking there may be some opportunity for that type of thing in real wardrobes, what with all the color-blocked looks out there 😉