Question about color blindness testing ?

Ok, I have a question for all of you optometrists out there. I am almost sure that I am color blind, and all of the tests i have taken online have shown that I am most likely slightly tritanopic. I think I am going to go to the optometrist asking for a test, but I know they will just use Ishihara plates to test me, which I hear are only for testing red green color blindness. My question is, do you have a test for patients with tritanopia/tritanomaly? If so, what kind of test is it? Is it usually expensive?