Australia has well managed seafood stocks. Seafood is quite affordable. Add to that the massive amount of competition. I live in the middle of suburbia and google maps has given like 7 different sushi places within a 5 min drive. Sub 50 AUD for sure. So <25 pounds or <35 USD.

While not exciting weather predictions and analysis is a big one.

Astrophysics is another popular one.

Anything where you need to do calculations that have large numbers of variables.