SSDs are great, but not at the expense of other things.
When building a gaming machine you always want to make sure your system is good before buying what I call "rich man toys". This means if the average price of an SSD is around $100, make sure that $100 wouldn't be better spent somewhere else. If you need to drop down to an i3, or get the 650TI instead of the 660 then maybe you shouldn't get the SSD. If you need to go down to a 1600x900 monitor instead of 1920x1080, then skip the SSD. They are like sound cards and fancy keyboard/mice. Great to have, but don't buy at the expense of the rest of your rig.