Amazon currently has a few Lego Technic sets on sale. Most of these are no longer on shelves and are extremely hard to find.
Service Truck (42008) $109.05 (was $129.99) - Shown above. One of the coolest Technic sets I own. When building it, we made a mistake in one of the gear mechanisms and I had to dismantle the whole thing to set it right. That's fun, right?
Mini Off-Roader (42001) $8.47 (was $12.99) - This little guy uses rubber bands for the suspension tension. I promise you will want to drive it over stuff to see the articulation the instant it is complete.
Monster Truck (42005) $35.70 (was $49.99) - Basically just a large version of the Mini Off-Roader but with spring suspension. Also awesome to drive over stuff and has 4-wheel steering!