Kevin,
The money may be better than doing a current owner search on the surface but the drive time to and from the closing and the time it takes to have the borrower sign the docs takes up more time than it does to do a current owner. It can take me up to 3 hours to fully complete a signing (including travel time). Signing agents are a dime a dozen, just like abstractors and most "signing companies" are only paying an average of $50 for a signing. I do most of my signings for title companies and they pay an average of $100-$125 and an extra $25-$35 if they need to email the docs to you and the packages are an average of 80-100 pages plus you have to make borrowers copies. 
I would rather do a current owner search than a signing. I can make $500 or more doing current owners in one day and complete them in 3-5 hours and only see that kind of money for 6-8 signings and that would take me 12 hours. I try to do signings only in the evenings, after my title work is done. 
I am not trying to discourage anyone. I have been doing this full time for 8 years. The first year or so was so slow trying to get a good client base and finding out who will pay you. There are some signing companies that do not pay their notaries after racking up a big bill for 30 days work just like title companies that do not pay the abstractors..  
You can go to www.gomobilenotary.com or www.notaryrotary.com and type in your zip code and the zip codes that you cover to find out just how many notaries there are doing work in your area.