The antonyms for the word "most dirtcheap" are expensive, costly, high-priced, dear, pricey, upscale, luxurious, exclusive, posh, and lavish. These words suggest that something is of a higher value or quality than something that is dirtcheap. For example, a luxurious brand of clothing may be expensive, but it is of high quality. An upscale restaurant may be pricey, but it provides an exclusive dining experience. The antonyms of "most dirtcheap" also indicate that something is not affordable for everyone and is out of reach for many.