It all depends on what you plan on doing with your machine, the more expensive boards will have a lot more features, more PCI-e slots, more Ram slots and better hardware support. You will get a better overclock on a better board (usually) and the more expensive ones tend to last longer and have better upgrade potential also not as important but is to me the expensive boards look freekin cool. In short if you just want a machine that works and lets say just want a low to mid range and cost gaming rig that has little to no frills then the cheep boards are the way to go. Also cheep boards are great if you are new to building PC's (or like i did built one for the kids) as most tend to be no fuss. If you want a machine you can push to the max with overclocking, obscene amounts of ram and 4 GPU's then you will need a better board
Edit: As a note though in some cases more expensive does not mean better some lower priced boards are fantastic value and can do most of the thing a high price one can (some research req).