My car failed inspection because of its evap system.

How much would it be to get my evap system fixed and where?

Now that's a good question; Why is it failing, is another good question; It needs to be tested to find out what part is wrong, to be able to tell you how much it will be. There is more than one component.

In regards to a failed emissions test due to a fuel evaporation control system failure the best advice is to get into a local shop that can has the proper equipment to test the system. Did you or do you have a "check engine" or other malfunction indicator light on? The problem can range from a faulty fuel cap, faulty vapor hoses or a faulty controlled component. The best answer to your cost of the repairs question is get a proper diagnosis and an estimate in writing that once fully diagnosed and repaired you will not "fail" the evap system portion of the test. Best of luck. Tim