You can build an RV7 for around 70k completed
Yea, $70K is probably a pretty close average, BUT... If you're frugal you can do it for a lot less then that even, I know of one completed last year for around $45K.
He did a simple VFR panel, got a high time used Lycoming and overhauled it himself, fixed pitch prop, did his own paint, and kept away from all the spendy options like custom seats, fancy throttle quadrants, electric flaps, and autopilot. Now he's got his own airplane for less $$ then a new SUV or ski boat. And as a plus, he can still add some of those fancy options later if he wants as his finances allow.
Of course on the opposite end of the spectrum I've seen pics of an RV-7 with dual Garmin G900s, custom leather interior, $50k paint job, composite CS prop. This guy literally had more $$ into his panel then many have in their whole plane.
That's the beauty of the experimental category... ... it can be as simple or fancy as you like.
EDIT: also I don't get why people are ragging on this guy for building in his basement. I for one admire his dedication. He didn't let any excuse like "I don't have a shop yet" get in the way of pursuing his dream. He thought outside the box and got it done.