Lindsey, The first thing these companies are going to ask you for is a price sheet.  They want to know what you charge for particular charges: i.e., 1 owner, 2 owner, 20 year, 40 year, etc.  You may want to work up a nice pdf to send them in the meantime. 

One Owner searches are generally billed at about $25-60 per search.  Just think about you time to do each search.  You also have to factor in your E&O insurance and all the other factors. 

You need to know what "Marketable Title" is in your area.  I live in Ohio where marketable title is considered 40 years.  That is because with most title issues, if it is over 40 years old it is past the statue of limitations in Ohio.  Therefore in Ohio you would do a 40-60 year search to insure you picked up any issues.  This is why you probably ran your Mortgages in O&G title back 40-60 yrs - you were running the Mortgages based on "surface" marketable title.  The same as O&G mineral title is a 150 year search.  That's to get back to the first O&G leases and severances in the 1860's.  Coal & other mineral searches my need to go back 200 years or to patent.  

For abstractors who started in O&G work one of the largest issues is they never knew WHY they were running title to a specific date, or why they were or were not pulling certain documents.  It has to do with legal issues specific to the purpose the title is being ran.  This is a big issue and one you need to understand to work on your own in the title game.  Your O&G brokers set those search specification based on attorney input needed to certify the title for its specific purpose. If you have a legal background, perfect.  If not you need to brush up on your title law for your area.

Once again, Good Luck.