Try Hawkins bazaar-they always have little nik-naks that go down well (i did that for my lad last year when he was 3).That aside what about things like accessories that go with his big pressies, a slinky, lego/playmobil people,craft items such as pom-poms/stickers/googly eyes etc.
Thomas the tank metal or wooden trains,plastic animals/dinosaurs,novelty soaps.