Where do you see this? I'm actually thinking of buying the software right now and I explicitly asked what other charges are there besides the initial fee (~$100) and they said there wasn't any. Am I not asking the right question?
I seriously doubt that it's just $100 -- but, I guess if you are making an application that you are just going to run yourself on a single machine, it would not cost much. The costs tended to increase with the number of computers you were deploying to. Or perhaps we used something more capable (does that come with all languages -- including Chinese/Japanese/Korean and RTL languages).
What kind of problem were you dealing with? Were you bumping up against any constraints?
I think we opted for the customer actually obtaining their Abbyy license from Abbyy in the end because of the licensing mis-match. We sold just the wrapper.
Our parent company was a big user of Abbyy, and I think had a totally custom deal. They needed it for all of the language support and similarly wanted the full power to run it at high-speed and inside of .NET programs.