If you want the most bang for your buck, you need to understand off-the-rack suits. They're generally cheapest, but the point of them is not that they're ready to wear. They are unfinished products, made to be altered. The point in an off-the-rack suit is that you buy it, take it to a skilled tailor, and (for a few hundred dollars) have it altered exactly to fit you. A well-altered off-the-rack suit will look quite good: not as good as a fully bespoke suit, but it'll be close.

(Provided that the initial off-the-rack suit is reasonably good to begin with.)