Upscale Design for Print

I already have the artwork saved as a JPEG/PNG, but the file is too small for professional printing. I need it rebuilt or up-scaled so it holds crisp detail at A4 size while remaining perfectly sharp when I send it to the press for my business-card stock... (Budget: $10 - $30 USD, Jobs: Adobe Illustrator, Adobe Photoshop, Business Card Design, Graphic Design, Illustrator, Image Processing, Photoshop, Print Design)