When James Hargreaves invented the spinning jenny in 1764, it sold for 70 British shillings. In 2014 this has the same purchasing power as around $924.
Hargreaves' daughter Jenny helped to inspire the machine when she knocked over a spinning wheel and Hargreaves noticed the spindle continued to twirl. Originally, textile workers could twist yarn onto only one spindle at a time; the spinning jenny allowed one worker to operate multiple spindles simultaneously. This development increased textile production by up to a factor of ten. Hargreaves is credited with helping to spark the industrial revolution in England because his invention enabled the creation of textile mills that encouraged workers to move to centralized cities.