Farmington Dragway

Here is an excellent source for just about any show in NC: http://www.cruisincarolinamagazine.com/
As far as Farmington goes: http://www.cruisincarolinamagazine.com/content/25th-annual-fun-run-car-show-mocksville-nc-2010
Not sure about any prices, info is a little hard to find online. This should be a good start.