Differences between Cheap and Expensive Motherboard

That a pretty complicated question, but it can include: quality of parts, quality of assembly, numerous specific features, compatibility, overclocking potential, upgrade potential, warranty, customer service, performance, tolerance for substandard components (not mobo), support for enthusiast tweaking, and the list goes on and on.

Some thoughts:
- quality of materials,
- VRMs design http://www.overclock.net/a/about-vrms-mosfets-motherboa...
- other features: number of PCIe slots, of SATA ports, performance of the audio controller, thunderbolt, Wi-fi, firewire etc included or not, power optimization, and other specifications that are advertised by the manufacturers.

the biggest probably is overclocking potential, cheap one's can't even oc.
then you those mentioned above, including board layout, power/reset buttons for convenience, looks, a lot more PCI-e lanes so it can support 2 or more GPU's, more power phase that helps OC'ng,
there are others... some boards are too expensive but there are good ones there that won't cost an arm and a leg

So if I just want to use core i3 3220 (that don't need to be OC) should I just bought the cheap one?
How is the difference about quality of material/parts between the cheap one and the expensive one? Is it worth to spent about $60-$100 more or even more than that? (I assume the cheap one is about $60-$80)

No need to spend on features that you won't use. But at the same time, I would choose a board from a known good manufacturer and check the feedback from users and reviews regarding that motherboard. A good starting point is newegg. It allows you to set options for narrowing your search. And you can check on their site other users opinions about the product.
Have in mind also the upgrading possibility and verify if the board will allow you to do that and what would be the boundaries.

thx everyone!  

edit: should I choose best answer? because I think everyone completing each other..

You don't have to, I'm sure we all appreciate your thanks more than the site score (:

Number of ports (SATA, USB 2.0, USB 3.0), slots (PCI-E, DIMM), and quality of VRM (capacitor brand, number of phases, power and current ratings of the MOSFETs)