round our way no-one hires entertainers and the parties are always great. at 4 a few games are good but don't over-organise as they all love to play with the new toys.
pass the parcel is a favourite. also biscuit or cake decorating - supply biscuits or fairy cakes and icing, sprinkles, silver balls etc and let them loose, then put them on a tray to go in the party bag at the end. popular with both sexes.
if you have access to any outside space then try a "treasure hunt" - just hide sweeties in the bushes!
some parents also do "pinatas" (not sure if the spelling is right). a colourful papier mache shape filled with sweets which the children then bash until it breaks open.
all very cheap and cheerful
good luck