How many hours of work does it take to earn enough to purchase a
hang glider?

According to the
US Bureau of Labor Statistics the average hourly wage for a production or
nonsupervisory employee was $19.92 in December 2012, working an average of 33.8
hours a week thereby earning $673.30 a week. I'd rather use the median values,
but the Bureau gives the average values, so I'll have to go with that.

Therefore it takes this average employee almost thirteen weeks of work to
purchase a Wills Wing T2C and a little over five and a half weeks to earn enough
to purchase a Falcon 4.

The equivalent weekly value for
December, 1976 was
$181.44. Therefore it would take you a little over six weeks to earn enough
to purchase the Wills Wing SST.

You mileage will most likely vary.