how much and how long to exsponge a felony

If it's a conviction it cannot be sealed or expunged. If you got deferred probation, and successfully completed it, you can have it sealed. To be eligible to have it expunged, the case would have to have been a dismissal, or an acquittal after a trial. The cost varies from attorney to attorney. Once filed, the process can take anywhere from 4-6 months, in my experience.