Is this a good price for a flight? Any tips for getting plane tickets?

Those look like pretty reasonable prices. There are no tricks to getting cheap fares. The best ways to do so are to book in advance (6-10 weeks in advance for domestic flights, longer for international flights or for travel at busy times), fly on less busy days (Tues, Wed, and Sat), and be flexible with your airports (you might find that another LA-area airport is even cheaper). But those do look like good fares.

I do notice that one airline listed is Spirit - be aware that Spirit has a lot of extra fees. They charge for carry-on bags, checked bags, for choosing your seat, for all snacks and drinks, for printing your boarding pass at the airport, etc. So that cheap fare could end up costing you more in the end. You can fly cheaply on Spirit if you're aware of these fees and know how to avoid them. The same is true of Allegiant and Frontier.

I think the price is pretty good. I would buy the tickets now before they go up.

Tips, book in advance, try searching different airlines, different airports,schedules and dates,since the fares are sold AS IS and will be affected by the amount of passengers on the plane, since everyone wants a deal the cheap fare will not last long and you might be left with premium fares. think the more passengers the higher the cost

What price do you expect? FREE
$89 is a low price and obviously $120 is more.

You just find out WHY one is cheaper.
Time of departure Flight Time Carry On Bag Charge, Luggage Charge are just some of things you add on to a CHEAP seat.
NO REFUND means NO REFUND. Read the details BEFORE you buy.
You can look on Airline sites directly.
There are not that many Airlines that fly from your location to LAX.

There are other nearby Airports too you can look at for possibilities. Burbank for example.

Little airlines always offer more attractive prices but most of them sell the rest of the stuff, for example might pay $99 round trip to LAX but might have to pay $20 for regular luggage and $5 for picking your seat.
My advise is to purchase tickets in advanced and with midium size airlines.