Don't spend money on ready-made banners and stands - they're easy to replace. Stretch a beautiful fabric between two chairs or attach it to the wall (a sheet, tablecloth, even old curtains work), and add a garland made from paper flags or balloons on a string.
Homemade props work just as well as store-bought ones: cut frames, numbers, stars, hearts from colored paper or cardboard and glue them to a base. You can gather some branches into a nice vase, arrange candles in jars, hang photos of the boy with clothespins on a rope. Photo props (funny glasses, mustaches, hats) are easy to make from paper, sticks, and tape - guests actually like those better than store-bought ones.