Let’s be clear, a “divorce” is simply the legal right to re-marry. If you are not married, you will not need a divorce. If you are married, you will most likely have other things you need to work out, like support, and a divorce will be just one thing you need to do.
To get a divorce, you need to fill out some papers asking the court to make an order. The cheapest way to get the divorce would be to fill out the papers together with your spouse, rather than having a lawyer fill out of the papers, and jointly ask for the divorce order. You can find the papers online, fill them out with your spouse and then bring them to the court to be filed.