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The cheapest way would be to have someone that shoots well to fire off a few rounds. If you are grouping all your shots low and to the right it is probably the sights.

To verify sights you would want a bench that holds the pistol perfectly solid to test. Otherwise as Tom stated having someone you know who is a good shot would be a second, but less reliable option. Chances are with the way guns are manufactured now it is more likely your technique. There are certain things you could be doing to cause the error. Many times if you shoot low and right (as a lefty) it could be because you are tightening your fingers while you pull the trigger, or jerking the trigger. If you google search diagnostic pistol target you can see some of the errors in techniques and what they cause your shots to do. I would take some time at the range and check your technique and maybe get some pointers from your range personnel. Most ranges have someone working them that can help you significantly as a new shooter. Just don't be afraid to ask for help.

Christopher, a great tool I have used is a cartridge Laser to check barrel alignment with sight point of aim. Example here so just get the correct caliber you use : https://www.budsgunshop.com/product_info.php/products_id/18187/aimshot+9mm+boresighter#