Didn't you have them done when you entered med school? Our med school covered this, as it was required for all med students. They also covered any vax/booster needed if titers weren't high enough. Same thing for residency (and my job as an attending); it was a condition of employment and I had to provide these records or be re-tested.
If you have never had these done, contact your student health services; if your insurance doesn't cover the labs, this is probably the most cost-friendly option for you. You can also ask if you need a doctor visit or not. Make sure to get copies of all the results to keep in your files for future documentation.