Go through your results for flights to Carlsbad California in the USA with Netflights.
If these flights are too expensive, try searching for a different time of year. So if your dates are flexible, consider looking at different times of year.
Or broaden your search by looking at other airports in the USA.
Looking at a few different departure airports will give you even more choice. See what you can find. And remember, it's best to book your flights in advance wherever possible.