The Lego Shop currently has clearance items for as much as 75% off. Shipping starts at $4.95. The Lego Fun Favor pack would make for some nice birthday favors. It includes: 4 LEGO Creator Airplanes, 4 LEGO Creator 4×4 trucks, 8 LEGO Club memberships and 8 LEGOLAND California or LEGOLAND Discovery Center Chicago admission tickets (with paid adult admission). It is $5.98 after 75% off discount.
My favorite are these magnet sets. They are $4.38 for the set of three.