Every component of a computer is important, but some are more important than others. Graphics cards are key for gaming, CPUs are key for workstation (and overall performance), and storage/memory is critical for data-rich operations. But there's one component that should never be undervalued....the motherboard.
There's a reason why this component is called the motherboard. Everything attaches to it somehow, and thus every other component relies on it. A solid motherboard will reward you time and time again, allowing you to add on more parts as desired..or upgrade current components without worrying about compatibility. Good motherboards will be loaded up with features from the manufacturer, and plenty of safety controls. Good motherboards will also support overclocking to a degree (superior overclocking motherboards are a different league).
Bad motherboards will have inferior sockets, poor layout, finicky power controls, and bad style. Now, this isn't to say that a lower-price motherboard is bad, far from it. Lower-price motherboards can be perfectly fine, just with less features/support. What to watch out for (or run away from) is boards with low ratings. Motherboards that have no more than 3 stars, or very few reviews, may not be a good choice to invest in.
Motherboards should be viewed as an investment, as they are a major pain to upgrade. Upgrading a motherboard always means taking nearly everything off (except drives, fans, and other things). Upgrading a motherboard can also mean upgrading the CPU and RAM as well, as the sockets may be incompatible.
You don't have to get the $500 motherboard, but I would strongly advise to spend at least $100-$150 on a motherboard. It won't give you the same rush as investing in a $500 GPU, or a slick SSD, but it will save you endless heartache (and lots of money).