Well, that's only a sideline.
5 seconds sound clip from the Gone with the Wind (1939) movie soundboard.
You can hear this line at 02:20:53 in the Blu-ray version of the movie.
Quote context
[...]
- Won't be long now before Miss Suellen and I can marry.
- Are you doing as well as all that?
- I'm no millionaire yet, but I've cleared a 1000 dollars already.
- Well, that's only a sideline.
- With all the good Georgia pine around Atlanta, and all this building going on?
- Well, all that takes money, and...
- I gotta be thinking about buying a home.
- What would you want a home for?
[...]