Most picture graphic programmes enable you to resize a picture, whilst keeping the original proportions. Of course, a little quality is lost, depending on the degree of enlargement from the original.
Doing it this way also enables you to make any adjustments to the picture; (lighten, darken, sharpen, trim, etc).
As regards cost, this depends very much on the printer. Looking at PC mag reviews of printing costs shows a considerable variation between makes/models.