I prefer to fly out of Newark since it's only 35 min. from home, but I can also fly out of JFK, Laguardia, Philly or even Atlantic City. Very helpful when getting cheap fares. Sometime you can get some crazy deals if you're willing to do weird things like fly out of JFK then come back to Newark. Hell, if someone's giving you a ride, who cares? Here just one sample of dozens of flight I found in the $400 range. Note, non-stop on the way, change in Frankfurt on the return. I just picked random dates, but it's usually cheaper to fly mid-week.
$253 + $139 taxes & fees = $392
per person
Leave
Wed, Mar 22 United Airlines 956
Depart: 6:57pm Arrive: 6:55am
New York, NY (JFK) to London, United Kingdom (LHR)
Non-stop * 6hr 58min * | Boeing 777
This is an overnight flight.
Return Wed, Mar 29
Lufthansa 4807 operated by Augsburg Airways
Depart: 1:20pm Arrive: 4:15pm
London, United Kingdom (LCY)
Frankfurt, Germany (FRA)
1 stop in FRA * 1hr 55min
* | De Havilland Dash 8 Turboprop
Change planes. Time between flights: 1hr 10min
Lufthansa 404
Depart: 5:25pm Arrive: 6:30pm
Frankfurt, Germany (FRA) New York, NY (JFK)
* 8hr 5min * | Boeing 747
Total duration: 11hr 10min
This particular sample was on Cheaptickets.com, but I found many similar on Expedia, Orbits, Travelocity, Cheapfares etc.
edit: OK, I just checked flights leaving from Atlanta and they are around $100 more. (bummer for you.) But that's still not really expensive.