Agency services arte going to vary state to state.  Calfiornia can be appealing as a corporate registration spot, so might demand a higher price, so check out online ... "Gooogle" it and see what the competition is charging.

In our area  it's not uncommon to charge $150 for a mobile notary signing service to meet you at a remote location.  Not sure if  your area will bear the same fees (cost of living differences and all, as compared to Silicon Valley metro area....)

Ancestry and a few other professional genealogy sites offer pro listings, so look about.  Ancestry's been buying a lot of them up, but there are still a few independent forums, listing, and ad sites to get onto.

Foreclosure listings are hot in our area as a thing we do too.  Selling subscriptions to data on new foreclosure properties;  abstract the assessment data, taxes due, other liens and email them to the subscriber.  This is faster data than RealtyTrac or Foreclosure Radar offer and specific to an geographic area that you investor needs.  Consider offering that too.