On some older cars replacement is as easy as popping out the old lock barrel and popping in another. Parts cost $20-30. Crooks do it all the time so why not you?
As cars get more modern the ignition locks become more difficult to replace. Some of the ones that have radio chips in them are probably best left to the dealer.
Go to your auto parts store and see what they have available. My son had an old K car and all it took was 2 minutes work with a screw driver.
Source: My son's broke down busted K car.