My only experience is with Medicann. To the best of my hippocampus, 135 evaluation and 90 re-evaluation; 40-45 off for disabled.. There are offices in Oakland, Concord, and Santa Rosa as closest to Napa. I've no experience with either of the two you listed but MMEC looks equivalent to Medicann.

"Cost varies by County. If you get MediCare/MediCal, they cut the fee in half, generally. Renewal process varies by County, so when you go in, ask them."
Have MMEC Recommendation, thoughts & help for MMIC? (Page 1) - Access Northern California - ASA Forum

This one says $66 with medi-cal or veteran status.
Latest News - California's Medical Marijuana Law -- Just a Smokescreen?

The process is pretty simple. Make an appointment and show up. You saw their list of ailments right?
All Ailments - Medical Marijuana - California - MMEC - Marijuana Medicine Evaluation Centers

If you still nervous about it download and read Senate Bill 420 and Proposition 215. Any questions just ask.
Legality - Medical Marijuana - California - MMEC - Marijuana Medicine Evaluation Centers