I suspect that they monitor the search and when they saw that people are looking for a domain they rise the price.
Acro,
You can disagree, all I can do is simply assure you (and put my name out there) and say that it simply isn't true. I've worked here for 1.5 years and know that we do not change prices based on user behavior. We do change prices from time to time based on industry trends (as everyone should do); but we don't do it due to a customer looking at a specific name.
All the best,
David