A septum is a wall of bone and cartilage separating the nasal passages which are lined with mucous membranes on either side. When the wall is severely tilted to one side that is referred to in the medical world as a "deviated septum". Visually you can tell when a septum has deviated because it looks like one nostril is bigger than the other.
A deviated septum, depending on the severity, can cause a number of health issues such as difficulty breathing due to disrupted airflow, headaches, facial pain, sleep apnea, increased rate of infection, and a postnasal drip. While in most severe cases surgery must be done because it is the only way to correct a deviated septum, there are other options available for a less severe case of a deviated septum.
Before opting for surgery which can be costly, require a recovery period, and has numerous risks involved, it is definitely worth it to look into some other medical treatments or natural treatments you can try, to alleviate the symptoms of a deviated septum and help facilitate better airflow in your nose:
One of the common causes of the discomfort and difficulty breathing with a deviated septum, is allergies and infections. One common medication you can use to alleviate the allergic reactions is nasal steroids.
Nasal steroids are prescribed or over the counter medication that needs to be used over an extended period of time to provide you with the proper relief.

The steroids reduce inflammation in the nose but can also have uncomfortable side effects such as dryness, stinging, and can cause your throat to be sore.
This includes any other allergy medications such as swallowable tablets. Choose a medication that doesn't cause drowsiness as it can inhibit your ability to drive.

In addition to the above mentioned medical treatments, there are also some more natural things you can try:
Nasal strips are that stick to your nose like a band-aid and have spring-like bands that lift the sides of your nose away from your septum and open your nasal passages to allow for better airflow. Generally, these are worn at night and can help with snoring issues. Nasal strips are sold at many pharmacies and do not require a prescription.

Nasal Dilators such as a Max-Air Nose Cones is another non-medical alternative to alleviating breathing problems. In order to determine if the Max-Air Nose Cones would work for you, you can try the "Cottle Maneuver". To do this, block one nostril and manually dilate the other laterally towards your cheek.
If there is an improvement in airflow then the Max-Air Nose Cones may be the right solution for you. The way the Max-Air Nose Cones work is that the gentle pressure of the cones opens the obstructed airway which improves airflow and makes breathing easier and more symmetrical.

The cones are customizable and can be bought in different sizes depending on the extent of the deviated septum. It can be worn individually if there is only a problem on one side of the nose.
Another great option that is nonmedical is the Nasal Valve SupportTM. It is a custom-designed, discreet, and reusable nasal insert that goes completely into the nasal cavity and eliminates obstruction in the front part of the nose and improves airflow without causing discomfort, irritation, or being noticeable at all to others. It's free to try with a 100% money-back guarantee and a 2-year warranty.

A nasal irrigation system such as a Neti-Pot, which is basically a water and salt solution poured into the nasal cavity, is a great way to naturally clear out mucus and relieve congestion. You can also buy pre-packaged solutions in squeezy bottles that will do the same thing. Make sure to use clean water to avoid infection.

Vaporizers and Humidifiers are small machines you can buy that add moisture to the air and help to relieve congestion just by breathing it in. Make sure the room in which you choose to use it has a chance to dry out beforehand to prevent mold from growing.

The steam from a hot shower does the same thing as a vaporizer or humidifier and can help to reduce nasal congestion.

If you have a deviated septum, make sure to avoid anything that can cause nasal congestion to be worse. Stay away from things you may be allergic to such as pollen, dust mites, animals, etc. Also, avoid being around smoke, chemicals, paint fumes, and other things that can cause nasal inflammation.

For someone looking for a natural therapy to help alleviate symptoms caused by a deviated septum, the Breathing Retraining (Buteyko Method) Therapy is an option. This method was developed in 1952 by Ukrainian Dr. Konstantin Pavlovich Buteyko and was designed to improve functional breathing patterns.
All people with deviated septum suffer from chronic over-breathing and need to normalize this hyperventilation. This form of breathing therapy trains your body to breathe slower and more regularly.
Combined with Buteyko's lifestyle guide to Sleep, diet, and exercise, this method is designed to improve the overall body-oxygen level. You can find out more about this therapy method by doing a simple google search. This method is used for a multitude of breathing issues such as asthma, epilepsy, and panic disorders.
Buteyko Breathing Exercises in 3 minutes by Patrick McKeown
Lastly, a new technology that has shown promise in small clinical trials, is the Vivaer Nasal Airway remodeling device developed by Aerin Medical. The device uses targeted energy to reshape the nasal passages and create better airflow. The procedure starts by taking a CT Scan of the patient's nasal cavity. Then the otolaryngologist (ENT) determines how the nose should be reshaped to maximize airflow. During the actual "surgery" the patient's nose is numbed and the radiofrequency energy reshapes the nasal passage. The nose heals over time and patients make regular visits to their ENT to ensure the procedure is working as planned.
Sources:
Alternative to septoplasty | HCF
How to Avoid Deviated Septum Surgery (ButeyKo Natural Treatment)
Sinus Obstruction Treatment Without Surgery
Deviated Septum Treatment without Surgery | Nasal Valve Support
I would like to get the surgery done and would like to know how much it cost.