ADWs get their feeds directly from the tote companies. All of them have an API for tote data.
If you are going to put out a commercial application, I would get the data direct from the tote. You can develop scraping programs as outlined in the link above, however you will be limited by your source for the scraping, and how often they update their data.
Price will probably vary among the various vendors, so it would pay to get them all to give you a quote. You could probably try the smaller ADW's (Premier Turf, The Greyhound Channel, etc) to see if they can provide it to you ... assuming your commercial use isn't creating an ADW yourself ...
