Now I've heard people refer to Mega Blocks as the poor man's Legos but this is far from true, especially in reference to the Halo series. While Legos have their blocky charm the Halo line is far from blocky. These are figures are fully formed mini- figs with ball and socket articulation and in my opinion the next evolution of the building block figure.
Gone are the squared legs and round pumpkin like head of their Lego compatriots. In their stead there is a fully sculpted figure ready to kick either Covenant or UNSC butt. Ironically the only evolutionary holdover from their Lego brethren are the hands, but in fairness to the Mega Bloks, they do have lines to indicate their fingers and what could pass as a thumb.
In addition the Halo figures also have knee and elbow joints. Though only simple swivel joints, they are amazing to behold on such a tiny figure. These joints add more depth to the poses that they can take. Especially since Halo figures can look up without having to lean back due the ball and socket neck it has. The possibilities of poses are greater than Legos.
If you like Halo and want figures without plopping whatever McFarlane charges (what, $10?) for their figures, try the Mega Bloks line. They're only $2.49 at my local Target and well worth the price in opinion. Or if you're daring enough, pick up a vehicle, you might like it.