How much can std testing cost?

Depends: There are lots of things that could be tested for including aids, syphyllis, gonorrhea, chlamydia, hepatitits, hpv, etc. Might need samples from mouth, vagina and anus. You can't test yourself very easily, you need swabs of body parts and blood tests to do it all. Cash paying customers frequently can get a discount. Uninsured patients might be able to get free testing from the health department.