Delta/KLM/Air France are offering flights from Austin to Belgium, Germany and Switzerland for as little as $514 round-trip. You can travel with these low, low fares from Austin in March, April, and August to December.
Momondo lists the same flights as low as $488.
You may find these flights listed on the Air France website, which may be codeshared with Delta.
Details are at https://escapeatx.com/cheap-flight-austin-san-antonio-germany-switzerland-belgium/