Devoted to lead generation, lead generators, and successful lead gen campaigns

I'm with Seth on this one. 

If you're going to say thank you as a way to encourage future business, or as a way to prompt customers to tell other people they know about you and generate sales leads for your business, you have to be genuine.

If you aren't genuine, you'll actually create animosity and bad will in trying to pass off a cheap imitation of the real thing.  Better not to say "thank you" at all versus saying thank you in a lame, cheap, expedient way...