It could still be possible for a dismissed DUI case to affect your driving record. You should check with the CA. Department of Motor Vehicles to find out what exactly will be listed on your driving record. The cost of a SR-22 in California will depend upon your driving record and other personal information.
Our online partner Esurance should be able to help you find out what the SR22 will cost you. You can get started on a car insurance quote with us here.